2 weeks of liquids

I got my approval for surgery late yesterday. Today I start the liquid diet. I would have liked to have more notice especially since my surgery date is November 15, 2010. That doesn't leave me a full 2 weeks for liquids. My patient advocate doesn't seem to want to answer my emails and the surgeons office is 300 miles a way.
I had knee surgery a month ago and am in a walking cast so haven't had the stability to exercise. I am so scared I won't lose the required weight in my 13 days. Do you think there is any hope?
I realy need to leave my own pity party and get proactive.