First of all, I’ll give my usual comment that most people will expect at this point. If you start on a plan, it’s usually best to finish it and decide what to change for next time around afterward. Scrapping a plan right in middle of it usually backfires.
That said, to answer your specific question, I would probably go with about 10 miles. If you’re training hard, 10 miles at marathon pace can be tough but not killer workout.