You talked about the buses - you meant buses from Warsaw to the airport? Are there night buses from Lublin to Warsaw
Yes, I mean't buses from Warszawa to the airport.
There are buses from Lublin directly to Warszawa aiport (and Warszawa itself, obviously) by Polski Express, but the earliest doesn't arrive until after 8am
There are normally frequent minibuses that run to Warszawa as well, but i couldn't tell you when they run or if they might be early enough for you to arrive on time. There are no night buses because the journey is too short (3.5hours).
You might be able to rent a car just for the journey and leave it in Warszawa at the airport, but it will probably be quite expensive (one way surcharge) and i can't help you with any details. Try emailing your questions to the Lublin tourist office or here