If possible, you should make sure his medication dose is optimized before he leaves for school. My niece’s medication needs to be tweaked every 2-3 years, it seems.
You might want to look into coaching–I believe both the Edge Foundation in Seattle and SALT at U of A coach long distance–these kids are so used to Skype/iChat that it is more familiar to them than being in a room with a coach. Having a neutral party coach him may help him respond to all the same good ideas you have fed him over the years 
The disabilities office will set-up accommodations, but they don’t usually coach, or check-up on a kid who isn’t using them.
Best of luck!