I've heard you can help speed the natural split in this way.....

Feed it well for a week or so. Then do a big water change. I guess the idea is to stress it a little bit. This way, it splits so that there are two chances for survival rather than one.

Anyway, this is what I heard somewhere. I don't know if it works. It makes sense to me. I thought that my green BTA was going to split, so I was ready to try it. Then it moved to a different spot in the tank and it didn't look like it wanted to split anymore. Strange thing, huh?