Every detectorist goes through 'slumps' like this,my worst slump period is when all your best permissions are under crop,so finds dry up and you then end up searching on pasture,woods infact it can get that desperate sometimes i end up hanging my detector up for a few weeks.
Then i wait till the old combines come out again and cut the barley and wheat,we use to have a reasonable amount of time before the land was ploughed and rolled again for the next crop,trouble is the time duaration between crops is getting narrower and narrower,on some farms we are finding that they could be seeded again within 7-10 days,which of course gives you a very small time duration before those fields are out of bounds again.
So i dont loose interest i even do river detecting and also magnet fishing off local bridges this keep my detecting of a fashion.
Its soul destroying when you start loosing interest because of a slump,change tactics,try new settings that type of thing could possibly help.
Good luck and hope you start finding silver again.