There is no functionality for AirBNB to advertise or flag anything special for potential guests. However, if you have lowered prices during a popular time frame, guests will likely find it themselves.
I recently saw a new feature where AirBNB asked us to drop prices 10% to attract last-minute guests, and it was an email where you could click through lower prices. The email claimed that if we dropped prices, AirBNB would email that new discount to guests.
I'm not sure if that work and is available everywhere or not--with summer almost upon us, we are nearly sold out and need all the "gaps" we can get to keep our home ship-shape.