How do I make my ex boyfriend regret he ever dumped me?

So I was with this guy in September of 2010. We met at Penn State my freshman year (this past year). Everything was great but we started getting more serious and he wouldn't ask me to be his girlfriend, he joined a frat, trust issues were flying everything. Long story short, he played with my heart so much, never asked me to be his girlfriend when i wasted all year with him trying, I did EVERYTHING for him. Needless to say, end of the year I said either take me seriously or we are ending it. He basically ended it. My heart was broken I felt awful, insecure. It was bad. I did everything for him. So currently I'm home for the summer. I'm wondering, when I go back to school how do I make him notice me? When I walk into that frat party how do i make him regret it? I have been working out, I got a new hair cut. I want to talk to other guys but I heard jealousy only goes so far. How do I talk to guys to not look like a whore and make him mad but make him crazy and completely regret dumping me? SOMEONE HELP PLEASE! :)