Does he have an IEP/504 for 2e remediation/accommodations at school? Is he transitioning to self-dependence with executive function (EF) skills? Is there a "go-to" person at school? Does school policy allow for early pickup, or are his requests for being picked up early from school outside the norm and being fulfilled as an exception to policy?
On one hand it sounds like he may need to gain skills in self-regulation, time management, and sub-dividing projects into smaller tasks then scheduling each task and holding himself accountable for accomplishing each of those tasks on schedule and/or identifying significant factors impeding his progress, articulating them, requesting help and/or advice... then correcting course and getting back on schedule.
On the other hand he may need or benefit from an alternative education, one in which he finds resources/opportunities which will help him prepare for college and/or career. What are his passionate interests? Is there a way for him to pursue those interests, starting from where he is now in terms of knowledge base, credentials, etc? If there is a gap in skills and/or credentialing, what must he do to enhance his skills and credentials to get where wants to go? Starting with a goal in mind and then reverse-engineering is often a good way to plan, and to tap into one's motivation.
You may wish to lay it out for him in those terms, and see if he has additional ideas. Then step back. Some may say that enabling a teen's over-reliance on a parent may be kicking the can down the road: He'll be a year older and still the lack the necessary life skills and study skills.
