I have been walking/running/hiking in my huaraches for about half a year now and have worn through 3 pairs of laces. I have been using accessory cord used in climbing as lacing material, since it has a high tensile rating, but it doesn't seem to be very abrasion-resistant. On my current pair of huaraches I have moved the side-holes outward a bit, which minimizes wear at those points, but the knot underneath the sole is still very vulnerable. What other lacing-materials are there that might last a bit longer?
As requested, I uploaded images of the huaraches and their current laces.

Side-note: For anyone interested in learning a good way to tie huaraches for long distance running visit this website for a great video tutorial.