I am having the same problem. I made a schedule that included 23 practice tests. When I went back to take my 13th today, I was not able to access the test. I have a note saying that I should "Strengthen Skills before test". The last few weeks I had not done any practice exercises, and I have just been taking practice tests. I am wondering if the system will now not allow that anymore. Worst comes to worst, I may just create a new account. 

Hello!

Thank you for your question - our LSAT section currently only offers 12 practice tests. Also, I am afraid it is not possible to reset the tests and do them again. To do so, I recommend you create a new account so you can start over. While it is not an ideal solution, it can serve as reinforcement of core concepts as you review and improve the retention of information and skills learned.

I hope this helps but please let me know if you need any further assistance!

All the best,

Alex