Did your client meet her goals? She may have just been a short term client who finished her package as planned. Were there any red flags along the way? You could e-mail her back and wish her the best and politely request an evaluation of your services. Do you have something like an “exit interview” summary that she can fill out regarding your services? Just a thought to get some feedback from your clients.
If she doesn’t respond, she may be ready to move on and you may never know the real reason. Then, I would just respect her decision and move forward.