The six series of chamber music inaugurated this season in the 475-seat Terrace Theater will be renewed next season, Marta Istomin, artistic administrator of the Kennedy Center, said yesterday.

The faces of the performers at the coming 31 concerts will be different, but the ideas and the themes will be largely the same. The boldest of the programs--the six-composer American Portraits series--will honor the reputations of six more venerable figures of the American scene: Virgil Thomson, John Cage, Milton Babbitt, Ornette Coleman, Ralph Shapey and William Schuman.

The emphasis in this series, as in the others, is on the broad range of chamber music, both instrumental and vocal. "The Terrace Theater is the natural home for chamber music at the Kennedy Center," explained Istomin, who is the impresario for the Terrace Theater concerts.

"We have such a variety of presentations here--in the Concert Hall, the Opera House and so on--there must be one place where you can go to hear this huge chamber repertoire in the best quality and for the music's sake," said Istomin. "And that is the way I want people to think of the Terrace."

Whereas this past season's piano series consisted of the 32 Beethoven sonatas performed by eight pianists, the new piano season will be devoted to romantic music ranging from the best known Chopin to the relatively unfamiliar sonatas of the American romantic Edward MacDowell, played by pianist James Tocco. Other pianists will be Annie Fischer, Bruno Leonardo Gelber, Coleman Blumfield, Lilian Kallir and John Browning.

Matched with the piano series is a set of programs that consists in large part of sonatas for more than one instrument. The first of that series will pair violinist Cho-Liang Lin with pianist Sandra Rivers. In subsequent programs, violinist Miriam Fried will perform with pianist Garrick Ohlsson; violinist Sergiu Luca with pianist Anne Epperson, and cellist Lynn Harrell with pianist John Atkins.

Two series will be reserved for larger ensembles. One will offer the Beaux Arts Trio, the La Salle String Quartet, the New Zurich Quartet, the Annapolis Brass Quintet and pianist Peter Serkin, with guest artists Cecile Licad, piano; Ida Kavafian, violin, and Rudolf Vrbsky, oboe.

Performers in the other chamber series will be the Guarneri String Quartet, the Norman Scribner Choir, the Prague Chamber Orchestra, the Orpheus Chamber Ensemble and the chamber group An Die Musik.

Istomin said that she scheduled only a few concerts by string quartets, which are normally the staple of the chamber music repertoire, because of the regular concerts at the Library of Congress by the Juilliard String Quartet.

The singers in next year's art song series will include bass Paul Plishka, baritone Alan Titus, soprano Phyllis Bryn-Julson, baritone Hakan Hagegard and soprano Martina Arroyo.

One thing that has helped make these concerts possible, Istomin said, "has been the willingness of artists to reduce fees and to play music that they have not done in a long time." The single tickets that cost $11 last season will go for $12 next year. Subscription seats will remain at $11.