Yes, the developer can be reused. If you plan on picking up where you left off the next day, cover the developer tray with a plastic trash bag, with the plastic in contact with the developer and the tray edges. It actually makes a pretty good seal . . .no oxygen, no oxidation ('cept what's dissolved in solution already).

If you are talking about funneling the developer into a bottle, and dumping it back into a tray later on, I don't think so. Too little developer, too much oxygen introduced.