I am sure we are familiar with shirt.woot and how they do that double take everyonce in a while to give those overlooked shirts or late entries another chance.

Bliuehouse should do that too, (obviously call it something else) but just do the same thing.  I really like the super hero design from like the 3rd week for example, there were a lot of cool designs that i think should have won.  You could maybe even do top two winners are printed, winner from the first week and winner from the second week and just let the voting role a long for two weeks and after the first week winner is printed just take that one down.

You may even want to allow themeless entries for this two week period incase some people have been saving some really sick art that has yet to fit any of the themes.  (a theme less entry could be its own idea in of it self as well)