Unjust Enrichment - Tenant vacates early?

[Michelle Elsaid]

If you have a short-term rental with no cancellation policy, and the tenant gives notice they will be vacating on week 1 (they fell at a restaurant) are you obligated to give money back if you re-rent the unit?

The contract states you are liable for the unit and there is no cancellation policy or refund. There is an option to buy "insurance" that was declined when making the reservation.