No. The pre-charge pressure for the bladder is lower than the operating pressure once it is placed into service. It functions based on the fact that the bladder was compressed when the pressure was increased in service. As fluid is lost from the system, the bladder will expand to push more fluid into the system so that differential pressure is maintained across the seal faces. If you had a permanently connected supply of nitrogen pressure, the bladder would not be compressed and would not function properly to maintain the seal differential pressure. Why would you want to have a nitrogen supply connected to the bladder? If you have leaks and are losing pressure, you should find and fix the leaks.
Johnny Pellin