- Start and save a new game. Remember the 4 digit ID of this save which can be found next to your save name.
- Open the save file location under User -> Your UserName -> SavedGames -> Grounded (may vary for you)
- There you can find now two save files starting with the 4 digit code of your new game. The one you created and the one the game created upon logout. Choose one which you gonna replace.
- Now go into your original World save which you wanna KEEP. Login, save, remember ID and logout so the game will create a logout save.
- Now find this save file in the save game folder (you may press F5 to update viewed folders). It should match the time and date of right now. Sort if if you cannot find the file.
- Copy the full name of one of your chosen new game files and delete the file. Now rename the manual or logout save of your original world.

You should now be able to load your original world under a new World Save. Played days will update as soon as you save ingame.

Done.