Is there something that you’re doing differently? Did you start acting any different once you started liking him that may have pushed him away at all? Maybe he thinks that you don’t like him and thinks you are still joking around. Does he try and make conversation? Or is it always you now? Ask yourself these questions. Be upfront and ask him. As much as other people will tell you, games do not work. Don’t play games to try and get his feelings out. A guy will appreciate you being upfront and not shy. Strike up a casual conversation in the hallway at school, text him, etc. After a while tell him. Go up to him and say, “hey, I like you. Not just as a friend, but more, and I was thinking if you felt the same way we could hang out some time?”, he’ll like the honesty. It also shows him you are confident. If he says yes, then great, and of he says no, then don’t act all awkward and clingy, be cool with it and respect his wishes.
Best of luck!