🚀 go-pugleaf

I have taught an AP physics course for the last four years. Every year at or
about this time the students that were bright lights in the first semester
have turned down their wattage considerably and are now, at best, dim bulbs.
  Those who were at least giving a reasonable effort last semester are now
toggled   off at the brain stem.  This is, of course, "senior slide."  To my
kids credit, they at least accept their bad grades and don't expect me to
bail them out some how.   But still, second semester AP has been and is a
frustating experience because of this (inevitable?) happening.  I doubt I'm
the only one who deals with this problem.   Does anyone out there have any
ways and means of dealing with this problem.  I'd love to hear.