Potty Regression

I'm not sure how it happened, but Tyler has been awful lately with accidents. He all of a sudden refuses to use the potty b/c it takes time out of his playing. The last few weeks have been gradually bad, but this week has been awful at school. I'm seriously doing laundry daily. We have tried punishing because we know he knows better, but it's not working. Next approach is reverse psychology with praise. I'm not sure why he needs an incentive again for going, but perhaps it's what he needs. Whatever the case is, it's not been too fun!