question, if i downloaded the old version and finished the game, how do i play the new update without losing my progress and restarting
You should be able to install the new version and play from your old saves.
I do some work to try and keep the story playable for older saves. Sorry if something breaks along the way, but 9/10 files should just continue like before.
Renpy (The visual novel program the game uses) keeps saves left over in an appdata file on your computer or phone. So even if you delete the game the saves should keep.