Sing a song for her,
how about this one.
If that doesn't work (which I can't think of any reason it won't) stop everything with this girl.
Judging from past experiences my friends have gone through, I must say it never ends well. You'll tend to be much too envolved in everything, constanly reading between the lines and going mad.
Let's face it, you're too enticed with this girl to play the game. In other words, Women tend to not want what they can have easily.
In other words, try it quickly. If you don't see results in say 3 weeks drop it. Move on, don't waste your senior year on one broad.