M.M.
My son didn't do much of the work he was assigned his senior year. he actually flunked English, they had semester classes so he did retake it before he graduated but then got by only by passing the final with a 93%.
He knew exactly what he needed too.
We dropped a bomb on him in December that year. He wasn't producing, he only worked at the pizza place and played video games. We said, we are not paying for college. At graduation you can move to these apartments at $500 a month and continue to work at the pizza place or pick a bootcamp.
He is now in the Navy and doing very well.
I now say to my 15 year old, Well there is always bootcamp. She knows I had money set aside for her brother that he did not get for school, nor did he get for anything else. I have some set aside for her. She also knows we are dead serious.
You can
Start talking to the teachers and get the due dates of the major projects
Then set up a time with him to get some of the work done at certain times, even if it means on weekends and the whole family is inconvenienced. He might miss Homecoming.
Let him fail while he is still in HS. He can still recover while at home and he may need a kick in the pants, like an F.
Have the coach talk to him or drop him from the team.
Take away the car and other "fun" items, electronics, phone, iPod, computer, tv. .