Did you mean private mortgage insurance (PMI) or homeowner's insurance?
I've had my homeowner's insurance fluctuate and I do periodically shop around to see what other companies offer, and I've gone in and adjusted my deductibles and checked about any discounts every year. You also have to take into account any catastrophic conditions (redrawing of flood plains, recent claims by their pool of insurers that make them think your area is a risk for something, etc...) You can always call them up and ask why they're raising your rates every year.
Might be time to shop around?