@Perry29 Anytime you decide to refund a guest, always make sure that the money you were owed (in this case the 50% you get to keep according to your policy) has actually been transferred to your bank account, paypal, whatever payout method you use. Hosts have run into situations where they refunded a guest only to have them apply to Airbnb for a refund as well and get it. So the host is out the $ twice.
I think it's not a bad thing to offer to partially refund a guest if you are able to rebook the cancelled dates. Goodwill and all that. They might tell their friends how nice the host was to refund when he didn't have to, and you might get more bookings that way.
But I think that even if you were to decide to refund a guest in a circumstance like that, you should keep back enough$ to pay yourself for whatever time you spent dealing with the reservation, messaging, etc. We shouldn't be expected to do anything for these guests, who are just strangers to us, for free.