I have found a few things help with traditional laces. I pull mine tight and when i get to the first clasps i pull the laces around each other and then the the second clasp and keep doing the same until the top. This is hard to explain but think of it as instead of crossing like normal laces the same lace stays on the same side of the boot the whole time.
If i could draw i would make you a diagram. Then at the top when you do your normal cross the laces and pull tight before doing the loops, cross it over twice, this kinda locks it in place before you finish the knot.
I don't know if any of this makes sense but mine have never really loosened when like this.
Ohh in fact i found a video that shows exactly what i mean. Traditional Lacing System - ThirtyTwo Boots - YouTube