If you want to recreate them onto Genesis, what 3doutlaw said is really the only way to do that. But there's no reason you can't keep using them the way they are. There are a ton of people who still stick with Generation 4 figures.

I don't often work with Gen4, so I can't tell you, off the top of my head, what is the best to save them out again after changing. But I would recommend ditching the old Runtime structure as you can sort and classify however you want in Studio (without ever touching Smart Content, if you don't want to).