So when you say “Day 6 will contain 2 new scenes” does this mean I need to go back and replay the game to see the new scenes or do you mean these are new scenes added to extend the game at the point it has ended currently (to further the story)?
The next update will contain 2 new scenes. It's new content that will extend Day 6 and the story. You will be able to play these scenes by loading your saves.
The next update will also include a "reworked" scene. And that will require you to start a new playthrough or load an older save if you want to play it.