Talk to him. If he still doesn’t seem to get it, you may have to just get him alone and talk with him. Be prepared that the conversation may not go the way you want so don’t get all your hopes up. Just tell him you’re interested in him and you want to go out on a date. He may be very flattered and impressed that you took the initiative and reciprocate his feelings. However if it doesn’t go the way you planned and he shows no interest, at least you know how he feels and there will be no “what if’s” you need to contemplate.
