Since the expanding the estate is the ongoing theme....
What about upgrading the pool to a essence fueled youth fountain (obviously making the girls younger...), maybe even adding extra functions per a pool menu like faster pregnancy, more stamina per month, lesser stamina consumption... so many options ^^
And since employes are already used, what about hiring a sexy female chef to the estate, boosting happiness and lowering maintenance ?
Although, a few pages ago someone asked about making money with the girls , and while I´m absolutely against pimping or sharing them, what about making porn with them ? You could use the normal sex-mode for that and base the income on positions used, both mc charm and girls beauty as well as her orgasms and where to unload mc cum.
This way all stats and traits are used, meaning maxing all out is a goal to work too.
After some fame gained with those (new stat or just number of films) you can expand the fetishes: daddy/ daughter pairing, breeding. first time, MILF.... Not to forget changing girl types to expand fan-base, or else lowering income through monotony.
When using a fame stat, gaining curious would-be porn stars per milestones as uniques with guaranteed perverted and extra high beauty would be a nice addition, as a special chara like Kimmy the shop girl.
Adding a BSM Dungeon to the estate and expand/ outfit it would add more options for sex in general and the porn making.
And it would allow to choose a domina from mc harem, using her to train submissiveness (based on her own lack of it and lesbian affinity, while relying on charmed stat to add own additions to said training....).
Lastly, as you can make girls more beautyful, maybe even younger, theres no way the mc wouldnt draw in girls and woman trying to get acces to such wonders.... (maybe even grey mouse to femme fatale mini stories ^^)
So big of a text-wall for now, I really love your game (I wouldnt get so much ideas for it otherwise...) and wish you all the best, keep those updates comming ^^