Gyroscopic Investing

Let's say you consider your cash slice to be usable as an ad-hoc emergency fund, and that you at some point need to use it, so you withdraw enough cash to hit the 15% rebalance band. Would you do a real rebalance, or try to make up the lost cash as quickly as possible so as to not have to rebalance?

I guess if the portfolio were relatively small so that I could get back to 15% cash within a few months, I wouldn't rebalance. Otherwise I would.