[Jim Sims]

You have more than a hose permeation problem - you likely have a damaged hose or leaking hose fitting or A/C system component. Find the leak and get it fixed.

A full evacuation and refill is not necessary provided the system pressure is still above atmospheric, one purges the refrigeration harness lines of air and you haven't lost significant oil - look for dirt stains just not oil as the R-134a refrigerant oils evaporate rather quickly. However the "auto parts store kits" are not adequate for recharging as the proper R-134a charge is determined by both pressure and temperature measurements - the cheap gage on the kits that merely indicates "full" can leave the system over or under filled. A reasonable quality refrigeration harness, a check valve equipped dispensing refrigerant can valve, a couple of bimetallic thermometers and a pair of safety goggles will run around $130 to $140 and you can reuse the gear year after year.