That's a good question! It's a trick question too!
Here's my thoughts on this...
It's not as obvious as one might think. You certainly don't want to do a secure erase (heck, you never need to do a secure erase unless maybe you want to sell the machine). And even a simple reformat is quationable.
It's not that these things won't work. It is just that the flash cells are not going to be reused unless there are no unused flash cells available. So you end up installing in unused flash cells which is not the same as when it was actually new.
So I don't know the answer here.
Note, I do recall the MacPerformanceGuild has some tool for reconditioning ssd's but I have to find it again and if I recall there was something that bothered me about its description.
Time for some google searches.
MPG Article on reconditing ssd's: Reconditioning a solid state drive (SSD)
I think what was bothering me about that article was the info near the end about writing over the entire ssd.
Another MPG Article: Restoring solid state drive performance with DiskTester ‘recondition’