Depends on situ. If I have bred them and had them a long time, I'll maybe move onto something new and maybe more challenging (or at least different). If I didn't feel like I accomplished anything with them, I will keep trying.
It depends on the fish. My silver aro jumped and died. I replaced him because the tank doesnt look right (atleast to me) with out that silvery body gliding across the top of it. I want to replace my planiceps too just havent found 1.