t's not as bad as it sounds m8. Firstly copy your Railsim directories "Assets & Content" to a safe place. Uninstall RS and make sure the RS directory has been erased. To re-install, "RS > Mk1 > and the latest version of DevTools". Then copy back in your original "Assets & Contents" directories you saved earlier, and ensure all copies of "Blueprints.pak" are deleted.
This all sounds a lot, but I think it all took me 30 minutes yesterday!