Independent writing is not particularly profitable, and it takes a great deal of time. If you want to help guarantee the future of this series, and ensure that books keep coming according to the great big game plan, there are some ridiculously powerful things you can do:
As you probably know this whole series is produced independently, without any backing from a publisher, agent, or marketing firm. It relies mostly on your word of mouth to generate interest amongst potential new readers! You are the best chance it has of continuing and growing.