Unfortunately, you also have fans who've played two titles in the series, plus a few expansions, and are starting to grumble for something different. By this time you've amassed a good understanding of what people like about your games. Additionally, from the lazy designer perspective, half of your feature set is waiting for you at the start of the project - everything you ran out of time for on the first game.
You know more about your team and ideally have a familiar engine and tool set to work with, providing you with a much better idea of what's possible. With your first game out in the wild, you're able to get real world feedback on what worked and what didn't. Two is easier, although you may not think so at the time. Mix these factors in with the usual chaos surrounding a game company on her maiden voyage and you have a situation often referred to generously as 'challenging.' Figuring out both how to work around long-expected pieces that don't pan out and how to capitalize on unexpected miracles is a big part of the job. Without an experienced team, much of your schedule operates at dartboard-level accuracy.
Without a prior success (or even a prior failure) for comparison, much of your design relies on instinct. There are a lot of things to attempt and reject, a lot of mistakes to make, a lot of lessons to learn.
