Generally I play from the last save (if the time between updates is short enough). Sometimes I play from an earlier save, to act as a recap. Sometimes, the last save doesn't work, so I have to play from an earlier save.
However, there are some games that wont play from a previous save at all (usually because the game version code has changed). If this happens regularly (Immoral Stories I'm looking at you), then I drop that game altogether.
There are some games though that are well written - therefore I will start from scratch again, just for the enjoyment.
Tip.... If you play on Windows 10/11 Ren'Py will create a roaming instance of the game that will remain until manually deleted. If you load the same game with a higher version it typically will see it and allow you to start from a save point without having to do anything. To make sure it works you should open the old game once, close it, then open the new version and all your saves should be there.
i reply from the start in most cases because if i liked it enough to download the update then i like it enough to see the previous content again the only exceptions to this is when it is a really long game like for example Four Elements Trainer it has 5 major chapters each with 2 alternate routes and almost all take up to an hour and a half to finish so for games like that I'll use a save
I always make a million saves like I'm gonna go back and try all the options (when not using a wtmod) but I rarely ever do, and then I'll go back to the game after so long that I just start over
For me it completely depends on the game. If the updates are often enough that I don't really have time to forget what happened in the previous ones I typically play from a save. If there's a long wait between updates I will usually replay from the start. If it's a final update to complete a game I usually will to a full play through just to get a look at everything one more time.
Depends on how long ago the last update was, also if the game isn't that great and the update takes so long I forget I'm just dropping the game at that point.
I usually start from the start, because that reduces risk of there being errors. Renpy especially is quite prone of fucking things up if you reload a save from previous version of the game.