Often I will improve upon my characters, but usually it's just technology to make them work better.
A few reasons made me change Elise quite a bit. Perhaps because she is one of my favorites. The biggest changes are her hair and her skin color. I wanted her skin color to closer match her mothers. I also like platinum blonde so I couldn't resist changing her hair color. The new hair is much more flexible and capable; also more realistic looking. The hair is the most jarring change for me, but I think I will get used to it.
Let me know what you think works well, or doesn't.