Donate them. Think of the closet space you will free up. Having nothing that fits is a great motivator once you have gotten rid of the old clothes. Save one size larger for those heavy days but toss the rest.
I'm finally back on fitday after having a bad few months. One of the main reasons is my fall wardrobe that fits is severely lacking and I refuse to buy new clothes when I have lots that will fit me if I lose a few pounds.
I saved maybe 3 items that I loved. You could also save your largest outfit just to show yourself what you have accomplished and where you never want to be again.
Keeping it off is hard. Having no larger clothes is a great motivator.
Restarting Jan 11th, 2014
Starting weight: 201.6
Current weight: March 7th 183.2
March Goal: 179.6
Ultimate goal Undecided ? 150 to be assessed once maintained for a while
Height 5' 3"