@Anna2417,
I wasn't suggesting that you take the booking off platform. I was trying to point out that if you have a guest that is making another reservation that will start immediately after the completion of the current one, that there be at least one day afterwards that the guest will not be able to book.
For example, your current guest is supposed to checkout on September 19, but has decided to extend the stay by two weeks. The space cannot be booked on September 20 (and 21, depending upon the preparation time that you selected under the Availability tab). By default, Airbnb has instituted a one day buffer between reservations. This means, your guest will have to send you a booking request for September 21 to October 4 (13 nights), and you will respond with a special offer with a rate that covers for 14 nights.