Came across this. We were in a similar situation. We called our insurance agent, they found us a company that was willing to insure our vacant home while it was for sale. It ended up being the only company willing to insure vacant homes in the state of FL: Lloyds of London. It was double what our regular home insurance was, but they allowed us to take out a 1, 3, or 6 months policy. There should be companies out there willing to insure your home. Call your previous insurance agent, or an underwriter at the 'big names'.
Are you still paying a mortgage? Your lender will probably allow you to use escrow money for this new premium. They might also take action against you/your loan for not carrying insurance on your home, so get on this fast!