it's the return portion of a trip, right?

if it's the first portion of a trip, you have to buy a whole new ticket. If it's another portion, you'll "just" pay the change fee

and any fare difference

Yes, return portion.

Gotcha Tara - I'll have to call them tomorrow and find out.

Thanks! Hopefully it won't be too much of a cost.

hopefully not - is this back to VA?

Yeah - I originally did it for a week+ but then decided I might as well stay til after New Years (given my situation)