The tour of Herman Levin's lavish, highly praised revival of "My Fair Lady," which was to have followed the New York run ending Sunday, has been canceled. It had been booked for June at the Kennedy Center Opera House.

Economics is the reason. It would have cost over $100,000 to break even each week, and for this reason some road cities dropped out of the projected national tour. In New York, Levin said that even the deferred tour, to have begun in Boston during May, has been canceled.

The admired revival had done well at 44th Street's St. James Theater, but was forced to move to the Lunt-Fontanne for "Music Is," which was expected to profit the St. James but instead cloed abruptly after five performances.

The two-block move cost the production $60,000, as much as it would have cost to move it to Boston or Washington. After that, MFL never did recover its box office steam. Cancellation of the tour, on which theaters in other cities had been counting, means that tours by big musicals are further endangered.

Remember Hollywood's old, famed pantages Theater? Opened for films and "stage presentations," as the phrase had it in 1929, this is the spot where the Oscars once were presented. Now it's coming back to the "live" fold, adding still another stage to the increasingly lively Los Angeles area. It reopened Tuesday night with a touring production of "Bubbling Brown Sugar," the original of which continues at New York's ANTA Theater.

With Martin Charnin credited as director for "Annie," what's the connection of director Mike Nichols with this Eisenhower-headed musical? Billed as one of four producers, Nichols saw the original last summer at the Goodspeed Opera House in Connecticut, admired same and proferred his "co-sponsorship." The David Mitchell settings for this adaptation of the Little Orphan Annie comic strip are new, and director Charnin also wrote the lyrics. The book is by Thomas Meehan, music by Charles Strouse, and previews will begin March 1 for a March 5 opening to run through April 2.

Richmond's Virginia Museum Theater, which introduced two of Romulus Linney's plays, has another new one by him, "Childe Byron." This concerns the life of Lord Byron as seen through the eyes of his daughter, Ada, countess of Lovelace. The author's "The Sorrows of Frederick the Great" and "Romulus" both bowed at VMT, where "Childe Byron" will open March 4 to run through March 26.

Casting for "a new form of folk opera based on Hans Christian Anderson's 'The Snow Queen,'" the Washington Theater Lab's Anthony Abeson is looking for a "multi-racial cast of actors of all ages, types and levels of experience." Details at 347-9415 . . . Howard University last night opened a "new, spacy" version of "Lysistrata," to be repeated tonight, Saturday and Sunday afternoon, again next weekend in Ira Aldridge Theater on the campus; details at 636-7700 . . . George Washington University Theater tonight through Feb. 26 will present "Richard II" in the Marvin Theater, 21st and H Streets . . . Mabel Mercer sings 'Saturday night at 8 in Lisner auditorium . . . Postponed during the energy crisis, the Children's Theater of Arlington will present "Sing Ho for a Prince" this weekend at Thomas Jefferson Community Theater. Details at 558-2161.

Unanimously favorable reviews greeted two New York bows, the National's recent "Otherwise Engaged" and "A Party with Betty Comden and Adolph Green." The later run is supposed to be for five weeks only but the songwriters' little revue is one Washington would relish.