If you have asked that question then this is the place to come, the solution is quick and easy. Go to this Sony page, print out the PDF file and voila, you have new AR cards to play with. I checked this out as I was playing PulzAR and wondered what would happen if one went AWOL, as this game needs all six.
I think with games of PulzAR's quality I'll be using them a bit more and the risk of losing one down the back of some furniture, or one of the kids desecrating them is ever more likely. Fortunately this fix is free and easy. Here's my page for other Vita-related advice.