I wonder if you considered leaving the previous project(s) running while adding new ones? Of course if you realized there was a reason they would never succeed,

I wonder if you considered leaving the previous project(s) running while adding new ones? Of course if you realized there was a reason they would never succeed, then terminate, but if you were unsure why they were not succeeding, maybe let them continue. An unused app is not a lot of work to keep running, right? You might collect a few users and one of those might give you a great idea. Customers can make great design partners, and the feedback on one app can lead to an improvement on another.