How can I make my ex want me back?

I broke up with my ex bf awhile ago, and recently I realized I want him back. We’ve remained friends & have hung out post-break up. I am going away on a 2 month vacation this summer, I see it as a good way to clear my mind about things. So right now i don’t want to try to8 get him back since I’m going on a trip anyway. But when i get back & school starts, I would like to get him back. He has been dating a few people & right now is interested in a particular girl. I’m not certain if these girls are his rebounds & he is trying to take his mind off me, or if he is truely interested in them & has forgotten about me. Not to sound cocky, but I am mostly counting on my looks to get him back. I am very pretty & the girl he is with is not at all. I mean she’s not hideous, but she’s a plain jane so it pisses me off. I know looks aren’t everything , but i’m hot! ughh. So what I want to know is if he really still cares for me & is using other girls as a rebound, but i guess u can’t tell me. SOOO I would really like to know what to do to make either him or his new gf jealus w/my looks or anything. PLEASEE HELPP!!