I've had to do this lots of times. It's really useful to be able to repurpose an existing project, but be able to rename text in namespaces, files, and folders (including file / directory names).
Using a recursive find and replace starting at the root folder means the rename doesn't break links to projects in the solution files and project references.
To this end, I have created a project to do just this. The application also makes an effort to ignore version control folders such as .git, .svn and the .vs settings file. More information is in the README.