As soon as I bought my garmin GPS and back pack tether from you a month or so ago I realised that the Velcro would quickly fray the cord. Simple solution was to wrap some black electrical insulating tape around the cord close to the Velcro part and problem solved. The tape will not stick to the Velcro as its too smooth.

Paracord is a great idea for a replacement cord, however would it not make more sense to thread the double length of the cord and the knot on the device end (the second knot you tied) through the shrink wrap. You can then shrink the wrap over the cord meaning it will no longer stick to the velcro. Rather than cutting the shrink wrap off after fitting.