You can put bots into the Recycler to get back the parts used to build them, or you can put bots into the Incinerator to just get rid of them, but why would you want to replace them with new bots? You could just retrain the old bots to do what you would otherwise make the new bots do. You could even use the Crude Data Storage to retrain an old bot to do the same tasks as another bot if you want.