Making a few huge assumptions--like, say, we can't undo the whole thing but we're going to make it right--I would institute a draft of people between the ages of 24 and 40. I don't think that this gets done well without an influx of people and I don't think that people who weren't in the decision make age group in 2002 should have to be the sacrificial lambs (Yes, this is partly an emotional decision, but there is a longterm need for manpower that isn't being met).
I would start the return of all national guard and reserve units back to the United States to fill their function of the strategic reserve. Train them and equip them.
I would send every available active duty Unit to Iraq regardless of their OPTEMPO. I need enough people in the country to hold ground and seal the borders. Other commitments in Bosnia, etc, will be honored but at a bare minimum.
I would limit foreign contractors and pump money to Iraqi's.
All of this is designed for one prupose, to put enough people on the ground to accomplish the mission--if that is a armored HMMV on everycorner than that is what I would work towards. Does this creat other vulnerabilites? You bet! The country decided to go to war, the country gets to pay for it--not 130,000 people that happen to be in the military and assigned to Iraq.
Conversly, we could just pull out, reset the sanctions, support our favorites and start over---but that is just a little to ootb, even for me--