It shouldn't be a big problem, the matching cards would keep their statistics and be linked from the new lists. So if you tested on HSK 3.1 level 1, the cards from HSK 3.0 that you had already reviewed would still be treated as already reviewed.
Ah, thanks, didn't realize the problem was simply that 'new' was incorrectly listing zero - I reproduced this here now so it should be fixed for the next beta update.
