NEW YORK (AP) _ Yes, Annie, there will be a ''Tomorrow.''

''Annie 2,'' a sequel to the long-running Broadway musical about the world's most famous orphan, will open in New York next March after tryouts in Washington and Boston.

''This story is not really as much a sequel as it is a continuation,'' says Martin Charnin, lyricist and director of the original ''Annie'' which arrived on Broadway in April 1977 and ran for 2,377 performances.

''The new show, which is subtitled 'Miss Hannigan's Revenge,' is a Crackerjack box musical,'' says Charnin, who again will supply the lyrics and direction.

The original ''Annie,'' based on the famous Harold Gray comic strip ''Little Orphan Annie,'' ended with the imprisonment of Miss Hannigan, the villainous matron who ran the orphanage, and the adoption of Annie by the wealthy Daddy Warbucks.

''In 'Annie 2,' which takes place six weeks after the original, Miss Hannigan is still in prison,'' Charnin says. ''Her one dream is to wreak havoc on Annie and get revenge. She succeeds in doing just that. But there are many other complications that will keep you on the edge of your seat, I hope.''

Rehearsals begin in October, with a first performance Dec. 14 at Washington's Kennedy Center Opera House where the musical will play seven weeks, says Charnin.

It will then play Boston, probably at the Shubert Theater, for four weeks, before coming to Broadway March 8, 1990. A New York theater has not been booked.

'''Annie 2' was an agonizing show to write,'' Charnin says. ''We went through three outlines and four drafts in seven years. Nobody wanted to just go back and do it again unless we felt we had something quite specific to contribute and had a way to make it fresh and interesting.''

Its pricetag also has changed. The original was budgeted at $800,000. ''Annie 2'' will have a budget of $6 million to $7 million, says Lewis Allen, one of the producers.

Much of the original production team will return for ''Annie 2,'' including Thomas Meehan, who wrote the book. Charnin and composer Charles Strouse will again supply the score, 19 songs in all. But don't listen too hard for ''Tomorrow,'' Annie's song of hope that was the big musical hit of the first show.

''There's only going to be a hint of it in the new show,'' Charnin says. ''It's like when you go to a wedding, even if they chose to play an original piece of music, somewhere in your head you hear Mendelssohn. Similarly, I don't think it's possible to go into 'Annie 2' and not, somewhere in your head, hear 'Tomorrow,' even if you don't necessarily hear it on the stage.''

Dorothy Loudon will again play Miss Hannigan, a role which won her a Tony Award 12 years ago. Still to be cast are a new 11-year-old Annie, a group of orphans and a new Sandy, Annie's faithful dog.

Charnin and the musical's staff are bracing for the open call auditions in New York on Sept. 11 and 12 for Annie and the other little girls. For two days they will watch children dance and sing ''Happy Birthday'' or ''Tomorrow.''

Three years into the original run of ''Annie,'' auditions for replacements were held. It attracted such a crowd of children and stage mothers that part of the street outside the theater had to be blocked off, Allen said.

Unlike Hollywood, where sequels such as ''Indiana Jones and the Last Crusade,'' ''Ghostbusters II'' and the ''Star Trek'' movies are an important part of film studio production each year, follow-up Broadway musical productions have been rare - and unsuccessful.

Among the attempts: George and Ira Gershwin tried it in 1933 with ''Let 'Em Eat Cake,'' a sequel to their political satire ''Of Thee I Sing.'' In 1981, ''Bring Back Birdie'' followed the fortunes of the characters in ''Bye Bye Birdie'' 20 years later.