Fixing laces..!

Hey there, I have Northwave Legend SL boots with that pullie tighten laces system. Works really great, but not as durable as I had expected..! I have a lace that’s starting to give out and I was wondering if there was a fix for this and if not, how do you go about replacing these?? I called my local shop but they don’t carry the speed laces system for Northwave, they said they only had Burton.