IT'S STILL HER PARTY

back in 1963, 16-year-old pop sensation lesley gore topped the charts with "it's my party." so whatever happened to the chirpy strawberry blonde with the beehive hairdo?

how about this storyline: the nice, multi-tasking jewish girl from affluent tenafly, n.j., went on to graduate from sarah lawrence college (major: english and american literature) and rack up another two dozen or so hits. when that gig waned, she turned to acting in summer stock, singing on the club circuit and discovering that she's gay. at 29, she and younger brother michael co-wrote "out here on my own," an oscar-nominated song from the 1980 hit movie fame.

after that, there was a quieter stretch of singing and songwriting. until 2005, that is, when she came out publicly during the release of "ever since," a collection of yearning ballads that showcased her sultry, mellow, grown-up voice. it was her first album in 30 years.

now gore, who turns 63 on sunday, is getting ready to write the second act of her life. literally. her dream is to complete a one-woman performance piece for off broadway.

"i'd like to get the second act done by summer and present it in the fall," she said during a recent phone interview.

staying fresh by exploring new material is crucial to gore's reinvention. it would have been easy enough, she notes, to simply perform in oldies-but-goodies concerts from here to vegas, with her yoga and meditation tapes in tow. but over the years, she's also sought out smaller, more intimate places for all her songs.

her newest venue will be feinstein's at loews regency. for her first time at this fancy supper club, she's bringing new arrangements and works for her four-piece band and three back-up singers.

of course, she'll perform "it's my party." but it won't be the version created by her original producer; back then, he was a newcomer named quincy jones. gore says he pushed her to sing at ever-higher octaves in search of a "young" sound. this is how he knew when gore had hit the right key: "quincy wanted to see the veins in my neck."

that would be a good story for gore's one woman-show. her project could also benefit from new buzz over fame. a remake is scheduled to reach movie theaters in september. (fiorello h. laguardia high school of music and art and performing arts, which is the new name for the original fame school, holds its annual fundraiser on may 3. one of the items to bid on in the silent auction is lunch with gore.)

next, gore says she'll focus on writing that second act in the upper east side home she shares with lois sasson, her partner of 25 years and a jewelry designer with an exclusive men's line at bergdorf goodman.

and if she decides not to work on the one-woman show after all, surely there will be other projects.

"this is a business-and life is a business-where you always have to challenge yourself," gore said. -- lesley gore may 5 to 9 feinstein's at loews regency 540 park ave. at 61st street $60 to $75 cover with $40 food/beverage minimum for tickets call 212-339-4095 or visit www.ticketweb.com