FWIW, I have a relative called Penelope who was Lolo as a baby. She wanted to use her full name when she started school, but her parents and siblings still occasionally use Lolo at home, and friends sometimes call her Lo. Lola, Lolo, and Lo are all pretty common diminutives for Penelope and Delores, although probably more so in Spanish-speaking countries.
Lola's sometimes also used for Charlotte, so I don't see why Lolo or Lo would be any more of stretch. Since this is for a teen rather than a baby I'd just suggest she keep generating possibilities, maybe run them by her friends or have them suggest some, until she finds one that she likes that sticks. She could also try Lotto or Arlo or Charo or Chaz or Chuck - it's not like she's going to be legally changing her name or anything, it's just for fun.