I've had issues with wading boot laces wearing out as well.

One thing that helps is to rinse your boots off after use. I believe the grit that accumulates on boots causes much of the wear. Rinse off the grit and you'll have less wear. Boots with fabric loop lave eyelets are worse, IMO, as they collect more grit and the fabric wears out too.

I've started replacing my worn outdoor shoe / boot laces with homemade paracord laces. Just get yourself a coil of paracord (I prefer the smaller "350" size), cut it to length, and fuse the ends with a flame. I haven't done this long enough to confirm durability, but the stuff seems pretty indestructible.