Retire geriatric breeding pair? Or keep going?

I just found out that my C nanoluteus (yellow convict) are 5 years old. Their lifespan is 8-10 years. They were housed in a large group at a friend's house for 5 years and never spawned. When I got them as a pair they spawned about a month ago. I'm concerned that they don't have a lot of clutches left in them and I'm considering retiring this pair (selling them) and holding back the nicest fry to create a new breeding pair, who would live out an incestuous relationship and crank out fry for me. Thoughts? Thanks!