It's worth a shot. Sure would be helpful if you decided to change a character's name. If not, I suppose I must go in chapter by chapter and change the MC's name from Lily to Emma.
What he said.A WORD OF CAUTION:
Think about what you are replacing for a moment.
Example:
If you are replacing the word "place" with the word "town", and you have the word "fireplace" in your document, you may well end up having the non word "firetown" in your document.
You might want to include the spaces before and after the word in your "find & replace".