To the best of my knowledge, the university I have an offer from does not require a deposit. I was merely thinking in terms of the April 15th resolution, which requires that i get a written release from the university that i accepted an offer from earlier, in order to confirm a new offer.
Of course, I understand, and i don't intend to do that. I was purely wondering what might happen if a preferred university that has waitlisted me makes an offer after April 15th.