Vocalist Julia Nixon has reinvented herself several times since arriving in Washington 30 years ago. Her latest recording, “Keepin’ on Track,” is a solo debut that explodes with gospel, jazz and her own thoughtful compositions. Her live concert at George Mason University’s Hylton Center revisits the numbers she sang in “Dreamgirls” and her days at D.C.’s Mr. Henry’s. “I’m excited about performing at the Hylton Center on my comeback trail,” she said. “I’ll sing Thelonious Monk’s ‘?’Round Midnight,’ some jazz standards and things I’ve written. I love a great mixture because I grew up listening to Motown, R&B, the Beatles, Sinatra, Sammy Davis Jr. and never locked in on one style.