But if you just can't give up?

Okay, i suppose this question is as old as life, but still, help. I'm in my middle teens, and the girl in whom i saw everything i ever wanted to see in a girl (and more) dumped me several months ago. Now, the dumping was rather radical and happened two weeks after our first actual date (although we started the actual relationship a few months before that). She stated that while she still loved me as a friend she really couldn't see herself dating me anymore. After that all sorts of communication we've had was rather one-sided, with her being distant and me being insecure. Now, i know simple truths like "sometimes you just have to let her go", or "she's not worth it, move on, there's be someone else out there who will really feel for you". But the thing is, i can't. It's been around 5 months already and i'm still thinking about her every day, still have feelings for her, and rather radically, i need her, i want her back, as pitiful as it sounds. I know what my obvious low points are (there's rather a lot of em, for the record), and i've been working hard lately to rework them. What i want to hear is some advice. What would help me in getting her back?