I think your best option is to call her work all the time ask for her and then breath heavy into the phone.
After that, follow her around to the gym, school, work, supermarket... where ever you can be near her, but not in sight of her.
Then escalate.... Neg her a bit by breaking into her house when she isnt home and steal all her panties. Women love practical jokes. EL OH EL!! Leave a big "I love You" in red lipstick on her bathroom mirror. For the added little touch, to let her know you care, make sure to leave small piles of your hair on her bed.
Beat up any other guys that you think may be interested in her. Start a slow leak in one of her tires. This way, as you are following her she will eventually get a flat. Voila! Since you have been following her, you show up and give her a ride. She will more than likely be very thankful, and will be quite impressed with the little jestures, that she will undoubtedly take you back to her place and sleep with you.
If you stick to the plan, you will win her affections back in no time.
Good luck bro.
CK