This makes a lot more sense than the current setup.
Not sure I follow exactly, but the point is really to encourage people to attack (and win), so if you don't get 5 stars in a 24 hour period, it makes sense that it should reset, and you should have to start over.
The idea that it would just reset at midnight (i'd actually make it like 3 or 4 am) in your local time zone could be the best solution, the only problem is that you have to make sure people can't game the system by switching time zones to reset the counter sooner, but there should be a couple different ways to handle this server side so it wouldn't be a problem.

