Personally I've played this game three times and I've always had trouble with money after a certain character has an accident and you need to pay $2000 I believe to fix them. Because also around that time (or at least around the time in my playthrough) you're given the opportunity to buy a really expensive elf, and losing $2000 makes it so much harder. I upgraded the bar to the max and it still took a long time to make enough money to buy that elf.
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I had the same problem in my first playthrough. Second time, after following the advice I got to focus on the bar as early as I could, I got closer but still ended up being in debt after the aforementioned accident. Third time, I found that the best way is - combined with the general advice about the bar - to simply limit yourself to interacting with just one of the girls per day once all of them have moved in. Sure, the plot may move forward a lot more slowly but I managed to make just enough money when it came to buying the elf in question.