You can cancel your trip and pay a redeposit fee to have all of you miles redeposited to your account. As previously stated, you can consider it the same as vacation insurance.

I did this 3 years ago after my husband lost his job and going to Europe for 2 weeks would not have been the smartest move. We couldn't rebook since we didn't know when he would get a job. At the time I believe we paid $50 per ticket to have the 90K miles (per person) redeposited. I rebooked 6 months later.