Are you able to possibly reframe it a bit? If he's into video games then maybe viewing the grade level class as grinding and the test as a boss that both lead to the same level up might help put things in perspective he can feel comfortable relating to. Maybe the grinding is boring, but it's part of a quest. Maybe defeating the boss just needs reading a strategy guide (or watching YouTube video nowadays).
Maybe alternative strategies to deal with the mismatch between knowledge and practice that take the pressure off of the repetitiveness? I dislike in general the idea that the advanced student helps the remedial students, but it might be an idea to explore. If you had a cooperative teacher you might work out an agreement where he still has to do a minimum number of actual practice questions, but then replaces the rest of that work assisting other students 1-on-1. He would get essentially the same practice, and it would give him some social interactions to make him more comfortable in that arena.
