Chris Potter and the changes
Chris Potter is obviously busy, if you notice on his IMDb page with his acting projects. Catherine Bell had to make a transition by forwarding the story to the future when her daughter is grown up and in high school. It doesn't mean that they can't make another film with Chris, but Bell felt a new regular series was in order and they had to make transitions. I have no problem with a doctor moving in next door and the debate between modern medicine verses nature's remedies. I found the series pilot to be interesting. I think they could throw in a new character as well. I like her daughter all grown up, but Bailee Madison is a seasoned actor that I like watching. I also like the new step son, [Dan Jeannotte], all grown up.
If Bell kept making films once a year with all the same cast, the overall story would get tiresome. Change was needed, and a weekly series was what many people wanted.