Assuming it needs to be replaced I have replaced pressure switch 1 year ago and added air to tank now I'm having rapid cycling I added air again and it appeared normal then 2 days later back to cycling too often.. what next?is it time to replace pressure tank if so what size?

With the pump shut off and a cold water tap opened to bleed off the pressure what is the tank charged at in regards to the cut in point of the control box? Let me know, tom