Repair or replace.
If the plug is assembled using screws dissemble it and use Chris Bryant suggestion above to stretch the sheath back out and reassemble it. If it is a molded plug, cut it off and get a good quality replacement.
The outer sheath installed properly helps in keeping the stress off the connection of the wires to the blades of the plug. Not repairing this means the wires will be pulled on which could cause them to loose their connection to the blades (as they are normally either screwed or crimped on). This will lead to a poor connection and voltage drops. This can lead to low voltages, which will stress the motors on the A/C and shorten their life. It also can lead to the connections getting hot, the plug melting and possibly fire.
Spend a few bucks, replace the plug and in the end, save a lot of bucks.
On Edit -
I just saw the OP post that he is going to use a " stainless steel hose clamp" to repair it. Do you really want to put clamp a piece of metal around a flexible cord where the flexing can enable the metal to cut through the insulation and short things out - or worse make contact to the hot wire then when you or one of your loved ones touch it to unplug it and they get electrocuted? Please dont be cheap! I dont want to read about you being killed by your power cord on RV.NET.
here:
$17.46 Camco 50Amp replacement cord end