Let's say you're writing a series of books with your main character (Let's call him Howard Gibbins) set in the 1770s when he's 10 years old. He's got a goal and during the course of the series, he accomplishes this goal after much trial and hardships. The series ends on a happy note and everything's all happy, fine, great. Now...let's say you want to start a sequel series involving our dear Howard Gibbins and all his friends (that are still alive), only now it's set years later...about ten or twenty years later. He's 30 years old in the decade of 1790. My question is: How do you make the new series just as good as the older one? The thing is, I've heard that sequels often aren't as good as the older series and plus, what if Howard had already resolved the big goal that had driven him on in the first series? What other thing could he do? Also, would it be too jarring for the readers if they pick up the new book and Howard is now 30? Just curious.