Andrina,
It's an interesting predicament you are in. That being said, there aren't many options other than what has already been listed here. Iron infusions may help, but keep in mind that iron infusions don't REPLACE blood. If you lose a lot during surgery, an iron infusion would probably be minimally helpful in the short term.
At this point, I think your best course of action is to talk to your GI and potential surgeon about your concerns. At this point, these are medical questions that should be directed to your doctor. Since you are refusing a blood transfusion under any circumstance, you need to make this a clear term going in, and make sure you have covered all possible bases with the surgeon as far as alternatives go. I agree with Jan that you may be turned down by some surgeons on these grounds so you must be prepared to up front from the outset. After all, this isn't something that can be remedied the day of surgery. I would imagine a feasible "back up plan" would have to be in place for you in advance so that any potential complication can be immediately and appropriately dealt with as it arises.
I hope you can find a reasonable solution. Even without surgery, just having UC, there may be times that your blood count is so low that a blood transfusion may be recommended, so you should already have viable options in place, IMO.