NEW YORK (AP) _ You can't keep a spunky orphan down, but leapin' lizards, you'd think the creators of ''Annie Warbucks'' would have done better by the little tyke who became famous in the funny papers nearly 70 years ago.

The musical, which opened Monday at off-Broadway's Variety Arts Theatre, is the much-troubled follow-up to ''Annie,'' one of Broadway's biggest hits.

The first show gave Little Orphan Annie a whole new generation of fans. It also introduced the song ''Tomorrow,'' now the unofficial anthem for every stage-struck girl under the age of 12.

For ''Annie Warbucks,'' long-time collaborators Thomas Meehan, Martin Charnin and Charles Strouse have saddled the kid with a thin score and an even thinner plot that only underline how difficult it is to do a successful sequel to a proven commodity.

There are no comparable tunes in this latest effort, which has gone through innumerable transformations since it first collapsed out-of-town in 1990. Its journey to New York has taken so long that Broadway buffs began referring to the show as ''Granny Warbucks.''

Considering the length of its gestation period, ''Annie Warbucks'' has arrived with the most uninvolving of stories.

The sequel picks up where ''Annie'' ended, with its red-haired heroine reunited with Daddy Warbucks. The only problem is that the wealthy Warbucks, a confirmed bachelor, can't adopt Annie unless he gets married within 60 days.

Who to wed? Warbucks hasn't dated since he went out with Woodrow Wilson's sister - it's now 1933 - and he considers himself an old man.

Of course, long-suffering secretary Grace Farrell is still in Warbucks' office, but her obvious acceptability is not noticed until late in the second act.

Gone - and much missed primarily because of Dorothy Loudon's definitive performance in the original - is Miss Hannigan, the orphanage matron who is now, according to the plot, doing 12 years in Leavenworth.

Replacing Hannigan as the show's chief villainess is a snarling commissioner of child welfare who spouts such lines as, ''A child doesn't need happiness. She need hygiene.''

As played by Alene Robertson, the commissioner is heavy-handed comic relief, and there's a desperation to Robertson's mugging that grows tiresome.

Harve Presnell, as the forthright Daddy Warbucks, manages to get more genuine laughs. He's a commanding presence, tall and with a big, booming voice that makes you want to stand up and salute. Yet his bewilderment at which woman to choose is touchingly funny.

Nine-year-old Kathryn Zaremba is an aggressive little Annie. Short of height, but long on moxie, she's a fighter who belts out her songs with confidence if not the articulation of an Ethel Merman. And she gets yeoman support from a laconic mongrel - real name: Cindy Lou - who plays her ever- faithful canine companion Sandy.

As one of the women contending for Warbucks' millions, Donna McKechnie brings a bit of dancing pizazz to the musical. She makes the most of Peter Gennaro's limited choreography and overshadows Marguerite MacIntyre, who's stuck with playing the lackluster and limp Grace.

Strouse's music, with OK lyrics by Charnin, doesn't rank among his best scores. It settles for the obvious, with more than a few songs sounding as if they were recycled from the previous show.

Meehan's book has a patchwork quality. Several episodes of the story are awkwardly stitched together, including one involving Annie's meeting with a Tennessee sharecropper and his family.

''Annie Warbucks'' looks modest, too, with cardboard flats designed by Ming Cho Lee that are undernourished even on the small Variety Arts stage.

Considering the show's turbulent history, you want to cheer it on, especially in its reduced, no-frills format. But unlike its predecessor, ''Annie Warbucks'' is a difficult show to take to your heart. Give it a half-hearted ''arf.''