Pretty positive you don't go back. Though if you got the money on you beforehand you just pay for it then and there. Maybe Zanith will add a scene to go back there at some point later down the line.
Since Yona was introduced Zanith's added in a dwarf girl (Blair), who is the final addition to the house I think, and has added in more story content for the other girls. Your mileage may vary, but I personally have enjoyed all the new scenes that've been put in. I think the quality is just as good if not better, they're always real fun, and Blair seems like a cool enough character.
The updates do feel kind of small when they come out sometimes, but Zanith's had pretty good consistency so far in getting the monthly updates out, and I think the quality generally has been pretty good so far, so I'm fine with waiting on the new content for however long it takes to finish if it stays as good as it is now. Besides, it's real easy for me to just download the update file and update the game so I don't gotta redownload the whole game every time.