How to "Break-up" With My Roommate

So, my roommate and I have had a fairly decent relationship rooming together this year.  There are only a few minor problems I have with her (mostly with her leaving the fridge a total mess - half eaten fruit that gets its juices all over the shelves, primarily - and me being the one to clean it up).  However, my best friend and I have decided that we want to room together next year.  The problem is....... how to bring up the subject with my current roomie.

It wouldn't be so much of a problem, and I wouldn't feel as bad, if it weren't for the fact that I'm not sure if she'll have anyone to room with next year - and she's told her parents that she really really likes having me as a roommate.

I really don't want to hurt her feelings, or leave her stuck out in the cold.  I am considering asking her if she'd like to be a suite-mate with us, since some of the rooms in the residence hall my friend and I want to get in to are suite-style, while others are separate rooms with community bathrooms.  However, I don't even know if we're allowed to request such things, or how we'd go about it (if it's the same form we filled out at the end of last semester, there's no option for that).

Basically, I could use some advice on how to bring up the subject and make sure her feelings don't get hurt.  Any ideas?

Thanks in advance!