I don't know if this is the same with all the other versions of the game, as I played the PC version only, but to copy the data of your saves, you can go through the files as such:
Perfect Love folder -> Perfect Love folder -> folder labeled "game" -> folder labeled "saves". You'll then want to select all the save files from the folder (you do not need to grab the file "persistent" as it's the only file that will stay after the wipe) and copy and paste them into a separate folder outside of the game's own folders (I named mine Perfect Love Saves).
Once you go through one of the True End choices, the game will force close and all the saves will be wiped. You'll then just copy over all the saves from the folder you moved them to, back into the game's own save folder. After that, you can reload the game and view the other True End choice (the saves will delete again after that).
You might end up needing to go through all the endings again if you load up the game first before moving the saves over, as that happened to me, but you can easily skip through them quickly.