The spot that you declined went to someone else. If they were to re-accept you they would have to take a spot away from someone who accepted their first offer. Unfortunately you will have to wait until the next cycle to re-apply.
But this is why you pay your deposit. I know sometimes it can get a little expensive, but you do it to prevent situations such as these. It's worth putting down the money now and be protected for the long term over being penny pinching in the short term and having to waste time and more money to apply the next year.