How do you reconnect with someone you were really close to?

My friend stacy and i used to be really close. we were like pretty close to best friends. im a guy by the way. we used to hang out so much and tell each other about everything. but when high school came, we grew apart. its now the end of freshman year and we really dont talk. she started hanging out with new people and kind of ditched me. now she hangs with all the cool people, and goes out with like the jocks at school. we dont even say hi in the halls, and i miss her like crazy. i really want to be friends with her again, but i dont really know how to. help?