I don't think there's much you can do. When a guy goes cold, that's usually it. My advice would be to forget about him and move on.
If you wanna give it one last shot, you can try one thing, and that is coming to a place where you know he'll be, looking super hot, like the best ever, and flirting with other guys and looking really happy. If he starts jumping around you, play hard to get, but still be flirty. Don't give in easily. The same if you sleep together again. Don't call him and give him lets just be friends talk, but keep acting like you're more than friends and deny it every time he calls you out. Push - pull game. Give a little, take a little. But always give a little less

It's hard to pull of when you love somebody, because you have to mindfuck them pretty much all the time. Well, that's the game.