Need a little info ---- Is it the fitting that was cut or the line itself? If it is a hard line it needs to be flared on both ends and then a piece of AC barrier refrigerant hose can be installed and clamped on using a clamp like this ----
Dorman® 800-670 - Line Splice Kit for 5/8" Line With #10 Hose
If it is a clean cut in the barrier hose a section of tubing with clamps on both ends can work -- do not use a repair tube like on a regular garden hose as the barbs will cut into the barrier hose causing it to leak. Both of these can work but it's a band-aid repair.
If it's the fitting at either end, take the line off, purchase a replacement end and have a hydraulic line shop crimp them on.
You can have new lines made, not cheap, but these lines are 20+ years old and prone to refrigerant 'seepage' and made for a now discontinued refrigerant. Do it right the first time - you will be glad you did.
[This message has been edited by steve308 (edited 07-13-2015).]