get a friend who is more attractive than you to lead her on then right when she leans in for the kiss yell "YEAH RIGHT! THAT WAS FOR JABRONI'S MOM!!!" then walk away
this girl lead me on for 2 months like left me notes in my locker and would walk me home after school and then i asked her to homecoming in the lunchroom in front of everyone super elaborate plan, and she said no..
She just has self confidence issues, you'll find that the people really worth dating are happy within themselves and don't have to take out their insecurities on you. Just give it some time, the right person will come.