You should make her jealous and have a battle between you and her current boyfriend. Make her realise that your worth another try.
get a new girlfriend or boyfriend
Thats impossible
It means that she wants her ex-boyfriend back even though she left him, and that she is jealous of his new girlfriend.
Just be her friend. Don't push it. If she wants you back, then she'll eventually come around. Don't stalk her or nag her on the phone. Don't be needy.
Well, people CAN change, but probably not.
It sounds like there are no signs.
Simple Answer: You don't.
You do absolutely nothing about your ex boyfriend considering he has a new girlfriend. If he loved you he would break up with his girlfriend and since he has not then he wants to be with her and you need to accept that. Just because you have broken up with your boyfriend it doesn't mean you can just step back into your ex boyfriend's life.
Let him have a threesome with your sister (only if hot)
You don't.. you wait for him to regret how foolish he was, and come back to you. If not, then it wasn't meant to be.
im sorry to say but get over hes gone
It's time to move on. Look for a new boyfriend. The longer you stay close to your ex, the more hurt you will feel. If he is a bad guy he can even misuse your feelings for him and get you in the sack, behind his new girlfriend's back.