Sometimes when kids wet the bed and don't want to change clothes afterwards it can be because the "wet" clothes feel warm or "secure" to them. I know this might sound odd and is not to be encouraged as it's not hygeinic and not a pattern that you want to get into, but it is also important not to shame your son.
What I would suggest is working with a therapist (if your son has been diagnosed with ADHD already I'm guessing you have a therapist?) on how to treat bedwetting-- to help your son stop and also to help you figure out how best to respond to it. Any psychologist who treats young children should be able to help you with this as it is a fairly common problem.