Every year at this time, it is customary to announce that a "new" theater season is upon us, when more often than not we merely mean "another" theater season. Our theaters promise us original plays or revivals of the classics so freshly interpreted they might as well be original plays. But generally, what we end up with is business as usual, more of the same, minor variations on a familiar theme.

This season, however, there may be some justification for thinking that "new" is a possibility. The thought is not so much prompted by the plays that have been scheduled, or by those particular actors and directors who will bring them to varying degrees of life. Rather, it's because the basic operating conditions at several of our theaters are changing.

Arena Stage, for example, is heading into its 35th season with a resident company twice the size of last season's. The expansion is funded by a National Endowment for the Arts grant that, among other things, allows Arena to put its company members on year-round contracts. This past summer, when actors, directors and playwrights would normally have gone their separate ways, they were already at work on upcoming productions -- among them Brecht's "The Good Person of Szechwan" and John Guare's "Women and Water," the third installment in his "Lydie Breeze" cycle. The upshot should be deeper dramatic delving and more persuasive ensemble acting.

The theatrical face of the Kennedy Center has already undergone a radical transformation under the adventurous prodding of Peter Sellars. Still, the last six months were just a beginning and 1985-86 will constitute Sellars' first full season as the director of the center's American National Theater. While his notions of establishing a free theater and importing regional theater productions, not to mention his own controversial stagings, have made waves, his battles against a deeply entrenched Kennedy Center bureaucracy have only just begun.

Sellars doesn't like to lock himself into long-range schedules (this, too, maddens the Center's bureaucracy) but he's announced a revival of Robert Sherwood's "Idiot's Delight" as ANT's first show in October, followed in November by "Golden Windows," a theater piece by Robert Wilson, and sometime thereafter, "Solo Voyages," monologues from the plays of Adrienne Kennedy, directed by Joseph Chaikin. Off-Broadway's Wooster Group will spend a three-month residency at the center, reprising old works and creating a new one. And there's a possibility in 1986 of either an O'Neill drama, Chekhov's "The Sea Gull" or a stage adaptation of Jack Kerouac's "On the Road." Whichever turns up, expect it to be unconventional.

More traditional Broadway offerings are scheduled at the National, and at the center between Sellars-generated projects. With such musicals as "La Cage aux Folles" and "Dreamgirls," and such plays as O'Neill's "Long Day's Journey Into Night" (starring Jack Lemmon), and a new Mike Nichols-directed comedy, "Social Security" (starring Marlo Thomas), the National has become the city's premier road house once again. The center, for its part, will host the Rex Harrison-Claudette Colbert vehicle "Aren't We All" in December and last season's Tony-winning musical "Big River" in February.

However, Broadway, which once accounted for most of America's theatrical activity, is gripped by ever-escalating costs, and its output dwindles from season to season. The Warner, which used to pick up a lot of the National and Kennedy Center overflow, doesn't have a theatrical booking until January, when the Stratford Festival from Canada plays a week of "King Lear" and "Twelfth Night."

The Folger Theatre nearly went under last spring, after the Folger Shakespeare Library, which had been covering the annual deficits, decided the company was too great a drain on its resources and threatened to pull the plug. The classical theater company has since won a two-year grace period, during which it will evolve into a financially independent entity. Just what shape it will take -- and eventually where -- are unanswered questions right now. But the new economic responsibilities are likely to encourage a greater conservatism that already seems evident in the lineup of popular, high-profile classics ("Othello," "The Miser," "The Cherry Orchard").

Ford's Theatre has a new artistic director, David Bell, who will emphasize musicals at the historic theater. Singer Barbara Cook is booked for an engagement in October, then Bell will stage a revival of the Neil Simon musical "Little Me." Bell's debut, last spring's revival of "Godspell," was uncharacteristically insipid, but he's made one welcome move: Ford's shopworn holiday attraction, "A Christmas Carol," has finally been shelved.

The city's smaller theaters have always been a mixed bag. New Playwrights' Theatre seems increasingly unable to resolve its shaky financial situation and, while it may be premature, several other theater groups are eyeing the space covetously. The Woolly Mammoth, for which a permanent home has become a top priority, will take off the first half of the season to find new quarters and not produce any plays until the spring. On the other hand, the New Arts Theatre has settled into the All Souls Unitarian Church for its first season in a fixed location, an encouraging omen. And the prognosis looks hopeful for the Studio Theatre, which recently negotiated a small contract with Actors Equity. Calling for the hiring of a certain number of Equity (professional) actors per show, the contract removes the Studio from the "amateur" ranks and should put it in a better bargaining position when it comes to securing the rights to original scripts or recent off-Broadway plays.

Broadway remains a powerful myth, however, and most people continue to think that its way of doing theater -- the out-of-town tryout, the frantic rewrites, the big make-or-break opening night -- is the predominant way. It isn't, of course, and hasn't been for some time. Most theater in Washington -- indeed, the nation -- is born of nonprofit organizations with a year-round life, a continuity of artistic staff and an overarching philosophy of what theater should be. As that support system evolves -- and signs indicate that evolution is under way -- the theater truly opens the door on the "new."

Here is a month-by-month look at the upcoming shows and the dates of their first performances: September

With a ton of feathers and beads, a cheerful score by Jerry Herman, a statuesque chorus line of men in drag and a titillating story line taken from the popular French film, "La Cage aux Folles" promises to be the season's big musical (at the National, Sept. 10). Vaudeville is not dead; the 1970s spawned a whole new crop of comics, jugglers and mimes, among them "Avner the Eccentric," who is a little of all of the above (Arena's Kreeger, Sept. 10). "Playing for Time," Arthur Miller's television drama about a French nightclub singer who survives Auschwitz concentration camp as part of an all-woman orchestra, has been adapted for the stage (Studio, Sept. 18). The 1962 musical "She Loves Me" was only a moderate success on Broadway, but it has long since acquired cult status (Center Stage, Baltimore, Sept. 20). In Moss Hart's comedy "Light Up the Sky," a group of temperamental theater people have gathered in Boston for the tryout of a new play (Castle Performing Arts Center, Sept. 21). William Gibson's "Handy Dandy" pits a law-and-order judge (James Whitmore) against an activist nun (Audra Lindley) who's taken up the antinuclear cause (Ford's, Sept. 24). The mischievous revue "Forbidden Broadway" spoofs musicals, stars, critics, composers and just about everything else connected with the Great White Way (Shoreham Hotel Marquis Lounge, Sept. 25). A woman exacts revenge on a rapist in William Mastrosimone's savage drama, "Extremities" (Source, Sept. 27). October

Jealousy, that green-eyed monster, devours the noble "Othello" (Folger, Oct. 1). The hit of the summer, Larry Shue's zany "The Foreigner," plays a return engagement (Olney, Oct. 1). "And a Nightingale Sang," C.P. Taylor's drama, spins a touching tale of love in Britain during the dark days of World War II (New Arts, Oct. 2). A rodeo performer and the woman who's crazy for him and equally crazy with him clash in Sam Shepard's "Fool for Love" (Round House, Oct. 4). In Bertolt Brecht's fable "The Good Person of Szechwan," a kindly prostitute discovers how frail true goodness is (Arena, Oct. 4). Betraying their true callings, one brother goes off to sea, the other remains on the farm in Eugene O'Neill's first full-length play "Beyond the Horizon" (Source, Oct. 11). Phoef Sutton's "Thin Wall" is described as a black comedy about violence in present-day Southern California (New Playwrights', Oct. 11). That sensational singer Barbara Cook bills her new program of songs as "A Broadway Evening" (Ford's, Oct. 15). Michael Moriarty and French film star Jeanne Moreau will head up the Broadway-bound revival of Tennessee Williams' "The Night of the Iguana" (Baltimore's Morris A. Mechanic, Oct. 15). Zona Gale won a Pulitzer Prize in 1921 for "Miss Lulu Bett," her drama about a good-hearted drudge who marries a bigamist (Horizons, Oct. 18). Under the horrified eyes of her mother, a daughter goes about the mundane business of preparing for suicide in Marsha Norman's harrowing " 'night, Mother" (Kreeger, Oct. 18). November

The musical spoof "Little Me" chronicles the life story of that legendary Hollywood film star Belle Poitrine (Ford's, Nov. 1). "Boesman and Lena" are homeless blacks, fated under South Africa's apartheid regime to wander the desolate mud flats in Athol Fugard's drama (Center Stage, Nov. 1). "Corpse!," a pre-Broadway mystery, stars Milo O'Shea and Keith Baxter (Morris Mechanic, Nov. 12). Donald Driver's family drama "A Walk Out of Water" cuts across three generations of an Oregon family, headed by a proudly stubborn grandmother, who is also blind (Studio, Nov. 13). Letters to the government from a broad range of American citizens are the basis of "Dear Uncle Sam," an original theater piece developed by the Paradise Island Express (National Archives, Nov. 19). A gullible young religious novice is the central character of the comic fable "The Man Who Killed the Buddha" (Round House, Nov. 22). Zoe Caldwell will be Lillian Hellman in the one-woman show entitled "Lillian" (Terrace, Nov. 25). The first play in John Guare's "Lydie Breeze" cycle, "Women and Water," shows the impetuous Lydie Breeze embarking on her search for utopia in the chaos following the Civil War (Arena, Nov. 29). December

Shakespeare is said to have written "The Merry Wives of Windsor" at the request of Queen Elizabeth, who wanted to see the blustering Sir John Falstaff in another play (Folger, Dec. 3). Rex Harrison and Claudette Colbert are the reasons to catch the revival of Frederick Lonsdale's genteel drawing room comedy, "Aren't We All?" (Opera House, Dec. 11). The crew from Peanuts romps through the musical "You're a Good Man, Charlie Brown," (Castle Performing Arts Center, Dec. 12). The shenanigans of Alan Ayckbourn's "Bedroom Farce" take place in three separate bedrooms in three different houses (Center Stage, Dec. 13). Clown and mime Bill Irwin calls his one-man show "The Regard of Flight" (Kreeger, Dec. 13). January

"Back on the Town," starring Nancy Walker and Liliane Montevecchi, revives a long-dormant Broadway form, the musical revue (Morris Mechanic, Jan. 7). In John Guare's wacky "The Landscape of the Body," a mother is accused of doing away with her son (Studio, Jan. 8). "Automatic Pilot," by Canadian playwright Erika Ritter, is about a female standup comic and the men in her life (Horizons, Jan. 9). "Sally and Marsha" charts the unlikely friendship between Marsha, a cynical New Yorker, and Sally, a do-gooder from South Dakota (Round House, Jan. 10). In "Restoration," England's Edward Bond combines the high jinks of a typical 18th-century comedy with contemporary political observations (Arena, Jan. 17). Sam Shepard explores a family's dark secrets in his Pulitzer Prize-winning "Buried Child" (Center Stage, Jan. 24). From Canada's Stratford Festival come "King Lear" and "Twelfth Night" (Warner, Jan. 28). February

"Big River," the Tony-winning musical last season, re-creates the adventures of Huckleberry Finn on the Mississippi (Opera House, Feb. 17). The selling of "The Cherry Orchard" signals the passing of a whole regime in Anton Chekhov's classic (Folger, Feb. 18).Andrew Bergman's comedy "Social Security" is set in New York and stars Marlo Thomas (National, Feb. 18). Romanian director Lucian Pintilie, responsible for last season's astonishing "Tartuffe," returns to direct Ibsen's "The Wild Duck" (Kreeger, Feb. 28). Mr. Biederman can't believe that "The Firebugs" intend to burn down his house, but they do and he even provides the match in Max Frisch's absurdist comedy (Round House, Feb. 28). Spring

The fatuous Arnolphe tries to train the perfect mate in Molie re's "School for Wives" (Center Stage, March 7). From the Tyrone Guthrie Theatre comes a stage adaptation of Charles Dickens' "Great Expectations" (George Mason University, March 11). Harold Pinter's "The Birthday Party" mixes menace and absurdist comedy (Studio, March 12). Jack Lemmon plays the haunted James Tyrone in Eugene O'Neill's "Long Day's Journey Into Night" (National, March 17). Philip Barry's most popular comedy, "The Philadelphia Story," recounts the tribulations of one Tracy Lord on her wedding day (Arena, March 21). The kidnaping and ransoming of a British diplomat by guerrillas is juxtaposed against the slaughter of a tribe of Brazilian Indians in Christopher Hampton's "Savages" (New Arts, March 26).

If there's a way to save a sou, Molie re's "The Miser" will find it (Folger, April 8). T. J. Edwards' drama "N.Y. Mets" is likely to be one of the plays in Woolly Mammoth's three-play repertory (April 10). "American Beef," a new play by Elizabeth Diggs, looks at a southwestern family that has the chance to sell its ranch to the government for $5 million (Horizons, April 11). The rise of a singing group not unlike the Supremes provides the story line for the Broadway musical "Dreamgirls" (National, April 14). Neil Simon's "Biloxi Blues," taking up where "Brighton Beach Memoirs" left off, shows us Eugene Morris Jerome, the playwright's alter ego, heading for boot camp (Morris Mechanic, April 15).

Shakespeare, never off the boards for long, is set for three productions almost in a row: "Two Gentlemen of Verona" (Round House, May 2), "The Taming of the Shrew" (Arena, May 23) and "Twelfth Night" (Folger, May 27). A woman named "Dorothy" and her family are swept up in the violence of Belfast in this 1980 Irish drama by Graham Reid (New Arts, May 21). Harold Pinter's "Old Times" lends fresh enigma to the eternal love triangle (Kreeger, May 23).