What happens next? I'm not going into details regarding plot, but more about process, and will be using films as an example ('cause I know you've all seen them).
The thing about writing a sequel is what's the key development of your character? The best stories are ultimately about the hero's emotional growth, but having grown immensely through Book 1, how much more immense must their growth be in Book 2? With Bond, he doesn't actually evolve in his stories (I'm excluding Casino Royale as it's a reboot, so shouldn't be considered as part of a series, will be interesting to see what they do next), he's the same at the beginning as he is at the end. Refuge is thus sort through spectacle as (lets admit it) the plots are pretty much the same. Which is why Connery was the best. In Doctor No and From Russia with Love, he isn't a superman, and the challenges are relatively small scale (from Russia with Love the whole plot revolves around he stealing a TYPEWRITER). But each challenge must be greater than the last, which is why it always ends up with FATE OF THE FREE WORLD being at stake.
The Bourne series tried to instill character development as the story does centre around him trying to discover himself (though I'll argue that Ultimatum was a repeat of Supremacy and actually the series was just one VERY LONG (but terrific) chase sequence) but did he actually CHANGE? He's still an ice cold operative at the end as he was at the beginning. Okay, he's disillusioned with the day job but hey, aren't we all? The story's about a man's mid-life crisis.
Granted, not all stories need to be based on the Hero's Journey (and if you're a storyteller, I don't need to explain this, do I?), but we are talking about the adventure the hero goes on MEANING something, rather than it being a recycle of what's gone before. To have meaning it must cause a CHANGE in the status quo.