K.G.
I've often read that the way to handle kids getting up is to go in and put them back in bed without saying anything or cuddling them/kissing them. Kissing or cuddling is a positive response to a somewhat negative behavior (since your goal is for him to stay there). If you kiss him or cuddle him, he will think it's a game and continue to get up. Maybe try your method without a few kisses . . .