Getting my ex back

Anastasia

My ex contacted me a couple days ago asking to hang out and catch up. I told him I was in the middle of stopping a thing with another guy and he said okay I'm gonna back off because I don't wanna get in between you guys. I told him today not to worry about the guy things are officially over. My ex was like my best friend and we would both do it over again but how do I get it back to flirting and kinda get him to really want me again?