How do you top success?

I finally gave up on Ben Bova's Mercury last night. I just could not get into the story; I didn't find it engaging at all. This is a real shame, because Bova is, in fact, one of the masters of science fiction. My available reading time is so limited at this point (although that will change next week!), that a book really needs to be a page-turner to keep me into it -- and this one just isn't. The story I' m working on currently is set on Mercury, but even that external interest couldn't get me to stay with the book.

Many of Bova's other stories, even ones in this series, are page-turners. But this illustrates a problem that I've been wondering about for a while: How do you top a successful book? Holly Lisle recently commented on her website that she's running into the same problem. She feels her new novel, Talyn, is the very best thing she's ever written, period. Everything just came together magically for that book. But now she's faced with working on her next book -- a book she says she is really excited about writing -- and she's too afraid of it to be able to work. What she's afraid of is that she won't be able to match the level of writing she achieved with Talyn. To make matters worse, she says she's not really sure where the magic that created Talyn came from, so she's not sure she can do it again. Now, Holly is a pro, and I personally think she's being too tough on herself. She writes good stuff -- and this opinion is from a guy who doesn't particularly like fantasy. But it does illustrate a problem that is increasingly becoming a big deal in today's publishing world: It's not good enough to write a "break-out" novel, you have to keep writing break-out novels. I used to read the Honor Harrington stories, and I distinctly remember not being able to put them down. As the series wore on, though, he just couldn't seem to keep the pace going (and the fact that Honor lost a body part in practically every story was getting a bit ridiculous). I can't bring myself to read them anymore -- I'd rather hold on to my memories of the earlier books in the series. The same thing goes for the Midshipman's Hope series. The first was one of the best SF books I've ever read, but they went downhill from there.

I know, I know, we should all have the problem of too good a success, but it really is a problem. How do we keep the momentum going in our later stories? A career is not built on a single book, after all. Maybe if we plan for the later books while writing the first one, the situation will be much improved, but I don't think it's quite that easy. How do you keep the same freshness and magic that created your blockbuster?