Companies have the right to choose not to renew your insurance policy once it expires. Depending on your state, they must notify you within a certain time period before the current policy ends to let you know why. Sometimes a company simply chooses to reduce the number of policies they provide in given area. Other times it could be due to the company discontinuing a particular type of insurance policy.
If this happens to you, don't waste time. Once you know your current coverage will not be renewed, start getting home insurance quotes from other companies. You want to make sure that you have a new plan in place before the existing one expires so there is not time in between during which you are not covered.
You can start by using a reliable site like QuoteScout.com to get a wide variety of homeowner's insurance quotes online. The faster you act the better your chances of finding a new policy in time are. You don't want to rush at the last minute and then settle for a less-than-ideal policy because you were going to be without insurance.