How do you update your project and change old options?

Hey guys!
It might seem like a weird question, but I'm not sure how to go about updating my game with new stuff and have it acknowledge that some things have changed.
From what I can tell, if you load a save file some things wont get updated, so everything that is NEW and shows up further ahead than the save file start gets updated, but things from before that have been updated just remains the same, like the window settings and changed variables and such?
If that is the case how do you go about updating a game if you need to change something from earlier.
Do you replay the whole thing?

 

Yes I replay it all. This is why I do major updates only when I'm ready to start testing from the beginning

 

When I want to test something further in my game, I simply create an event at the start of the game that sets my stats to what I feel is appropriate for the area. Then I have it flip whatever switches, or set variables are necessary for that portion of the game. And finally it moves me to the map in question, occasionally with a changed player sprite because I find something funny.

 

It depends what's in the update.
If it's just some text or cutscene, I just test that part with the required parameters (regardless of any save file).
If it's changes that impact the whole game (new system, ...) not much choice but to to replay the whole game or at least a good part of it.
Then you also have the case when what you're changing can have unforseen consequences on some other stuff, and you'll also want to make sure that doesn't happen.