Okay so with all of your hard work and talking to your amygdala and riding out a panic attack, the panic will definitely lessen but I am hesitant to say that it will go away completely (but for some people it might!). For the rest of you, it definitely won't bother you as much, and you will be able to continue to live a normal life but it would be a lie to say that you will never have another panic attack in your lifetime. So I consider this to be a "remission". In medicine, remission means that you have a chronic illness but that you are not experiencing symptoms at the present time.
Unfortunately, bad stuff can happen - maybe you lose your job or a parent is sick and you start to feel a lot of stress. The symptoms may slowly start to creep back up to you. You have to try and recognize that you are feeling this way because you are stressed out. Not because you have a life-threatening illness. With this new stress, it is possible that you will relapse a little bit into your old state. Try to use this knowledge to your advantage and practice the skills that you have learned. What has happened to me in the past is that I will be stressed out about work or relationships or what have you and have a couple of days where I am experiencing a few panic attacks per day (which I ride out fine). But when your body goes through a bunch of attacks like that it can start to take a physical toll. Suddenly you are hyper-aware of every little sensation in your body and your muscles are probably really tight and sore - this can create anxiety. Recognize this series of events so you do not think something is wrong with you. Yes, you might feel out of sorts for a few days after the fact. Don't let this turn into a cycle of thinking something is wrong, having a panic attack and then feeling worse and then worrying and then having another attack etc etc. Remember that during a stressful time, a relapse may occur. That is okay. Deal with it the best that you can. Remember that your body might not be quite right for a little while after that but that is normal and nothing is wrong with you. You are not spiraling out of control, you are not going back to the beginning. You might have a few "off" days, but everyone does right? With our disorder you have to make sure to recognize that this is normal, it is part of being a human being and you will feel better shortly. Keep a positive attitude about your condition. Attitude is everything with panic disorder.