<p>It takes a lot of energy to go thru 4 years of college. That is why there is a debate whether undergrad should be completed in 3 instead of 4 years. I don’t blame your son’s lack of enthusiasm, it just gets boring in the junior year. Anyway, what you need to do is to talk to him gently and keep reminding him about his responsibilities. Also make sure that he has or make friends and goes out rather than play video games at home all the time. Those who socialize are usually more aware of their responsibilities. What you can do is give him money like $20 or something to go out for bowling with friends and stuff.
There is no one way to get your son motivated again, its a hit and try technique.</p>