N/a, Windows 7
May not apply directly to what you're doing but I had a similar problem and here's the solution I figured out, at least for an HP LaserJet 2025. I am using OS X and iOS 7.
In the Printer Setup settings an option exists to go show printer "Webpage" for settings and monitoring statistics. In the Paper Handling option of the Settings tab you see a set of options for "Paper Out Handling." One option is wait for tray to be loaded, and the other is specifiy time and option. This allows you to set how many seconds it will wait if the queued paper tray is empty before taking the next action. In my case the two options for next action are Cancel and Override. Cancel will stop the print job (and in iOS using AirPrint you get no feedback other than walking to the printer to find no print job went through).
However, Override is where the solution begins. It will direct the printer to use the next tray that has paper in it.
Try using the AiO Remote App to select Paper Source.
Tray option?
