If you still want to be friends with him, then try talking to him this time around. I know that you may think it's a bit odd since he's so outgoing, but maybe right now he's waiting for you to make a move for whatever reason. Either that or you two don't have a lot of classes or activities together anymore and he's just worried that it'd be awkward. Things like that is quite normal and happens all the time. In order to reconnect the lost connection, simply take the initiative to talk to him more often. There could be the possibility that he no longer wants to be in contact with you but that's not really likely. You should go for it and try talking to him before you make any judgments.