@Steven65
Hi Steven, I have this situation come up frequently and the best way to achieve this is....
Ask the guest to hit the contact host field on your profile page! They will be prompted to put in dates they would like to stay.
This is not a reservation request Steven, it is simply an inquiry but, what it does, it opens up a pricing box on the left of the existing message stream you have with this guest which, at present, remains blank because their previous stay has ended. Under that new pricing box you will see a field that says 'Send Special Offer'. So, at this point they have not booked, they have simply made an inquiry for specific dates. Hit that send special offer field and this screenshot of mine which will perhaps explain it better will appear Steven.......
By scrolling the up/down arrows you will be able see not only the price the guest will pay but what you will receive and the Airbnb service fees.
When you are happy with the offer, hit the 'Send Special Offer' red feild, and that is all you have to do. As soon as the guest receives that offer, they accept, and Steven, it will be set in stone.
I hope this helps mate,
Cheers......Rob