Thanks a lot! As for buying the game again, I'm not entirely sure itch.io tallies previous purchases and I can't find anything about it in the FAQ. So I assume you'd have to buy the game for the full price. I see no way to issue individual discounts either, so that's a shame. :(
No sequel unfortunately, I'm hard at work on my next project. I'd like to do some Sisterly Lust short story DLC at some point, but I really lack the time currently.