It's great to hear that the therapy series has helped you. Give yourself credit - you did the work! That is no small feat. Sticking with a daily habit, any habit, that is the persistence needed and not always easy. Congratulations!
Should you repeat the series? In my opinion, it can't hurt. It can only help. And from my experience, it helped me to repeat the series. I needed to repeat the series, and I feel most people that I see here do too. It makes sense - we've lived this long with social anxiety. Yes, we're changing our brains in the right way now, but years of habits and thoughts - well, the more time committed to changing those thoughts, the better. And most of us need more time than we may think when we start out.
When I went back through the series the second time, different things stood out and became relevant for me. I responded to messages that I didn't quite get the first go-round. And then I continued to "do" the therapy in other ways, after going through the series more traditionally, let's say - as in from start to finish as I did the first two times. My therapy later became more customized to what I needed and how I would "practice" it. I think it has to change really, to stay fresh, to keep up with you at that moment. You're not the same person as when you started the series the first time. Like an exercise routine at the gym. You get down the basics, a really strong foundation, and you're smart enough and self-aware enough to tweak it as you need.