Re: Repair or discard?
First, look and see how far you go before you start to hit front taper. If you are still in the level tip, just cut it and you are good to go. Many lines have more than a few feet of level tip.
I have not really experimented much in repairing them so hopefully if you are up in the taper, there is someone here that knows a way to fix it. If not, sounds like new line time.
If you do experiment with fixing it, make sure the core is dry before you do it. Maybe something like the plastic coat for electrical or tool handles.