Like you I've already started worrying about how I'll maintain my loss bit premature I know. However the plans I already have in place are:
1) Continue to weigh in every week. I'm not necessarily gonna be too bothered if I put on a lb or two once in a while, but will be able to monitor so the lbs don't creep on unnoticed. I can just cut back a bit if I see those numbers moving up.
2)I'm gonna get rid of any clothes that are too big for me. If I have to go out and buy a bigger size if I'm too naughty, think that may deter me.
3) I'm gonna keep coming on here. Keep posting, offering advice, and getting it. There's plenty of people around here to keep you in line. Will make sure I post any gains, just to see it in black and white, and to stay accountable.
Like I say that's a long way off though. Go my goal of 168lbs which will bring me to healthy BMI, but after that my 'real' goal is 150lb, and I do keep in mind that's where I'm heading. i'll celebrate 168, but I sure as hell aint stopping there.
Good luck and see u in maintenance.