I have a guest who has made a booking but took a long time to make other enquiries. I sent a special offer but now the booking has expired. Can we still use the same booking or do they have to rebook through the airbnb system to get the same dates?
If the guest allready made a booking, why sending a special offer ?
If you want to apply special discount, the confirmed reservation should be changed.
A booking can not expire (a booking REQUEST can expire), unless guest do not pay within the 24 hours time limit.
Please explain more clear what your question is. If there is no booking and the guest only sent an INQUIRY (which you pre-approved ), then simply sent the special offer again.