Glad you're enjoying it! Not sure how the gamejolt client does things, but save files are located here: Windows: C:\users\(username)\AppData\Local\UserData\Default\Lust Doll Plus
Mac: \Users\(username)\Library\Application Support\Default\Lust Doll Plus
Linux: \Users\(username)\.config\KADOKAWA\RPGMV\Default\Lust Doll Plus
(May need to sudo nautilus if you don't have access to .config)