"I've always had a show that went seven episodes or 13 episodes or whatever. And I've never had a show that's gone past a first season. It really is a lot of work"

Leah Remini is referring to her experience in the tv market. She has had a variety of programs that have just lasted for a couple of episodes or a single season. This is likely due to the quantity of work that enters into developing and preserving an effective show. It takes a lot of effort to produce a show that will be successful and last for several seasons. Remini is most likely revealing her appreciation for the hard work that goes into developing an effective program, and her understanding of the problem of sustaining a show for multiple seasons. She is also likely expressing her own experience of having programs that have actually not been successful enough to last beyond a single season.