Just don't talk to her, if she really wants you back she'll come back, you've already stated what you wanted. If ya keep asking its gonna really piss her off.
Ya know, girls are relatively easy to get, with some of them you have to kinda freak them out, not like pop up and scream at them but just kinda play mind games.
Heres one for instance, pick out one of the hottest girls and just walk up and say "hows it goin?", if she replies just listen and make a small conversation and leave. If she is like "Eeew get out of my face freak" then just walk off, then the following day just ask her again, its gonna confuse her and kinda freak her out, cause she just told you yesterday to get lost. Well do that until you can get a conversation out.
It actually works with some girls wierdly enough

You can't take anything they say personally though cause you will loose all self esteem and wont bother to try anymore.