Is there a way to make a mostly-automated cleanup of exception lists? Something like, PL checks the list against executables and processes that aren't installed anymore, and removes them from the list?
Nope, as it only remember the process name, not the path and process name.
One of the easy ways is you open the prolasso.ini, and find the process name, clean it up.
This would require too much guessing and overhead, and never be comprehensive since many processes are launched from temporary names, or run 'from' the network.
A 'last seen' date might aid in manual cleanup, but that would be overkill.