Hello,
Sorry that the lack of restart is frustrating you!
Although there isn't a hard reset (unfortunately this wasn't possible due to the structure of the acts) there is a Demolish tool in the Foundations menu. This allows you do remove all rooms, items, buildings etc from the level and sends all of your exhibits to the inventory. This allows you to start from scratch, build your own building how you want and slowly add back in rooms etc as you need them so you can expand as your finances do.
If you're struggling financially it may also be worth looking at your current staff and weighing up if you need as many or if you could get by with lower level staff who have lower salary expectations.
I hope that helps!
Chizel
Please can a way to restart individual levels be added because it's really frustrating that isn't an option.