I believe you should be able to. Here's what happened to me:
I had the first set of full length tests completed shortly after I had received my Liberation Key. Recently, when I selectively began Perceptual Ability Test 2, I realized this test had earlier been started by me probably with the intention of making sure that the program works or in need of getting used to mechanics of the test then. I immediately stopped it as I realized the time remaining was less than 50 minutes and several answers had already been marked.
When calling up the seller and explaining to him on this, he did a wonderful job to me via some kind of simple file exchanges. Not only that the PAT 2 was reset but those that I have completed remain intact and untouched with the score reports, which serves critically to monitor my progressive performances on all attempted mock exams.