Re: I am going to lose it!!!
My dd was totally trained for 3mos and then regressed. She's not as uninterested as your ds but what has seemingly motivated her at least a little is our casual conversations like involving things she can't do because she pees in her pants.
I took her to the mall and we stood outside this really cool play place and talked about how fun it would be to go there and then I said casually "they don't let girls in who pee their pants so maybe we can go when you don't do that anymore" I could see little wheels turning in her head...
It wasn't a bribe or anything, just a statement of fact that there are certain things you miss out on in life if you insist on peeing in your pants!!!