There is actually a way for (at least paper) gliders to perpetually stay aloft, though this assumes a wing design that generates its own reverse wind current. In a standard Flying Wing design, the wings have two flaps that help stabilize the craft, however even it, if it ran out of fuel will eventually falls to the Earth below.
Lets say instead, you had a wing design whose flaps curved was downward, and its each curve had its own separate downward curve that simulate how birds generate their own wind current. With a slanted angle, and the edges starting at the middle have almost a spiral like curve downward. Then simply straight out both wings.
What you'd have is a paper glider whose curve is slight, but whose curve varies based on the closeness to the edge. The curve eventually curve below the handle, making the craft stable. So you have two different wind current trying to play tug of war with each other.
This keeps the plane aloft for far longer than a conventional paper airplane.
To propel it, simply drop it straight down, but don't throw it. The wind current will flow through the curved edges propelling the craft.
