Yeah, the GMATPrep software is really, really frustrating in some ways. The IR and AWA questions are the same, it's really difficult to review questions after you take a GMATPrep exam (if you close the software, your answers vanish), and I've had all sorts of problems with crashing software and disappearing GMATPrep Question Pack exercises on my Mac. I could go on and on about the problems with the software.
Supposedly, GMAC is releasing an update this month that fixes some of this stuff:
6-key-takeaways-from-the-gmat-test-prep-summit-147705.html. I'd be willing to wager that some of the glitches will remain, and I'm not holding my breath for a release in the next two weeks, either. But maybe we'll eventually get some relief.

You probably already know this, but you can access an additional bank of IR questions using the code in the back of the 13th edition of the OG. It's not the same as having a real practice test with non-repeated IR questions, but at least you can get a little bit of extra practice if you need it.