I agree with both Fran and Wiped Out.
There may be ways to get that carrot, though, without him really getting anything "extra". For example, if the clothes in my house don't make it in the hamper, they don't get washed. I don't go looking for clothes anymore. I will say, I'm getting ready to do laundry. Do I have all your clothes? 5 minutes later whatever is in the hamper gets washed. Nothing else. When they no longer have clean clothes to wear to school, they become motivated.