An automatic replenishing system for automatically replenishing preservative gas within a compressible bladder for supply to the inner volume of a vessel. A compressible bladder has an outer wall and an inner volume. A supply conduit receives preservative gas from a source, and a discharge conduit supplies preservative gas to a vessel. An inflation detection system detect a first condition wherein the compressible bladder is inflated to a state of inflation and a second condition wherein the compressible bladder is inflated below the state of inflation. A valve system is operative to prevent preservative gas from flowing from the source of preservative gas and into the compressible bladder when the compressible bladder is in the first condition and to permit preservative gas to flow from the source of preservative gas and into the compressible bladder when the compressible bladder is in the second condition.
