Man, reading an early access VN sounds like agony to me - not because I disagree with the concept but rather due to my tendency to devour stories in the shortest time I can. Having to wait on the story piecemeal would suck.
Any idea why they require a new game with each update? Are they making technical changes that make the old saves incompatible or export game in a way that makes it act as a different title? If I recall correctly, Ren'Py keeps saves in proper system location rather than the game folder so they should be still there.