Lately she has started to clean up without me reminding her. The other day we were playing with her train set. She went and brought a bin with a Zoo set in it. She put it down and indicated that we needed to clean the train up first. She did most of it by herself, and then set to playing with the zoo.
Once I told my husband to tell her to clean up with him and he thought I was nuts. Like I was punishing her. I encouraged him to do it and see that she actually enjoys it. To his surprise I was right! To her cleaning up is just part of the game.
Now I can't say we always clean up like this. Sometimes we get distracted, or she gets upset and we leave things out and I clean them up on my own later. I am hoping if we keep this up, cleaning up will just be something we always do and won't be a big deal.