How about an "Old Peoples Home" for all those generals, explorers and geologists who have past their prime? If you change your mind and want to re-use one or more, then the medic general could pop in with a potion and rejuvenate the required retiree.
This would remove some of the clutter from the star menu, and save all the frustration of trying to sort through so many every day.
I know theres a couple of other similar suggestions, the prison and the recycler, but I think a retirement home would be kinder... they wouldnt feel so unloved as if you threw them in the recycler