Hey there, I'm glad you've been enjoying it so far 🙂 Each download is the complete game, so all you need to do is delete the old folder containing the previous version of the game, then launch the game from the new download. All your saves and unlocked images are in another location on your computer, so they'll still pop up in the new version when you launch it.
There's also the Itch.io desktop app you could use to just update without needing to delete anything. They have info on it here: https://itch.io/app
As for recommendations, the related games link at the top of my game's main page brings up some good options. Coming Out on Top was a big influence on this game, and it was Summer Vacation that inspired me to try my hand at making a VN myself.
Giving book recommendations from the previous genres I wrote in would be too big a hint as to my actual identity, so I'll have to be coy about what I'd rec related to those 😉