If a soul is what makes you, you, then I think it's pretty close to what the worlds I come from call a "heart."

People without hearts have memories of the people that they were, but they don't really feel anything. It's like they're just pretending. But I've learned that even people without them can get them back eventually.

You probably don't even really realize when it starts to grow back - or grow at all. It just does, slowly. Then before you know it, you're not just acting on memories anymore - it's genuine.