Find a different insurance agency, an independent one that represents many companies. They should be able to find you a better rate.
When we first bought our theatre, Motorists was the lowest.
But my agent looks around every year, and a few year's back Auto-Owners was the lowest. And Auto-Owners has been the lowest by far ever since.
And my theatre is a twinned small town theatre built in 1938.
Also, my liablity rate is based on attendance, not box office gross.
It was that way for Motorists also.
So as I have raised my ticket prices over the years, it has therefore not negatively affected my liability insurance.