Depends on how you modded it. No need for CFW if you use the FTP method to overwrite the files when the game is already installed.
I think you still need CFW or signpatching if you use the pack-unpack method.
You need CFW for the SDCafiine method.
how do u do this? the OP makes it sound like you cant use ftp for this. "(no, FtpiiU Everywhere does not let you rename a folder in a game you've already installed, unfortunately)"