Sit/Down

I don't know if it because I am working on drop on recall and rewarding dropping so heavily but Wyatt is going down a lot on his group sits (never a strength anyway). I am backing up and staying in sight and using shorter times. I always wonder what the best thing to do is when this happens: start again from scratch, pull him up, use my up command to get him up, etc and then if I should reward since he went down during some part of the exercise...