The Sequel

I am about to embark into sequel territory.  It's not necessarily a sequel in the sense that you have to have read the first book, and there's no mega cliffhanger in the first one demanding a second.  It's a sequel in that the story takes place after the events of the first book (GET WELL SOON) with many of the same characters.  The setting is very different (outside of a mental hospital, as opposed to inside), and the story is different (coping with life post mental hospital, as opposed to in mental hospital).  So maybe it's just a follow-up?  Whatever the label, I have to write it this summer.  And I'm nervous.  I think there are bigger expectations--from me, yes, but now from other people who have read the first book and want to hear the same voice and revisit the same characters.  I don't want to disappoint.  And I'm also nervous about revisiting those depressing feelings from high school.  I am kind of kicking myself for taking on such a tough novel.  I didn't think it would be tough at first.  A sequel?  Same characters?  Picking up where I left off?  How could that be difficult?  But I'm scared.  This is the character that is as close to me, in my depressed high school state, as it gets.  And here I am, inserting myself back into her ratty Converse and tragic brain.  The first step is to re-read GET WELL SOON (which brings up a million changes I'd make now, as an author with three novels under her belt instead of none), make a list of characters and stuff to remember, and then I'll start writing.  Next week.  Anyone out there who has written a sequel have any advice to offer?