I'm in the middle of a refactoring project, but it doesn't involve any code, and I happen to be the client.
In the process of re-insulating the attic, we discovered that the wiring and electricity in our house is FUBAR. So our electrician is redoing all of the wires correctly. This is a refactoring effort, because after tons of effort, hopefully there will be no difference in functionality. The only difference should be less buggy, more maintainable, more consistent electricity, and the ability to renovate.