I have never felt the need to rename one of my characters. I choose a name and I trust in that name. I have a couple of characters in my current WIP whose names aren’t sticking for them, but I think it’s more about me not knowing them than the names not fitting.
If I were renaming one of my characters the first thing I would do would be to figure out why I chose the first name. I chose the name Rachel for a friend character because I wanted her to have a common name to contrast with the lead character and to subtly indicate that her family is Jewish, but I sometimes find myself calling her Ashley. It’s another common name that would suit the character, but I think the reason why I kept calling “Rachel” “Ashley” is because I subconsciously knew that Rachel should be like an Ashley whoI know: A bit bitchy and whiney. Now I know what I liked about the name and what was “wrong”, and I know that I can fix it in the rewrite.
If knowing why you chose the name doesn’t help you see a change like it did for me, you could then think about how that name is restricting the character. Is the name too formal or flowery for her? Does the name remind you of one type of person but the character has evolved into a different type? Did you choose a name based on its meaning rather than on its feeling?
Once you’ve discovered what you want from the name and what isn’t working, then throw out the name and go back to the drawing board. Look at your list of names (if you have one), go to your favorite baby name website or to the Social Security Administration site, or ask your character what he or she wants to be called. Start by thinking of the character your problem character interacts with most. Does the problem character need a contrasting name or a similar one?
The most important thing about renaming a character is to not let it get in the way of the work—the writing. When you have time, think about it and try to find something that works. When you don’t have time, just keep swimming along with the rest of your story and trust that the right name will come.