The path has been in place nearly 8 years and had gone from a width of 3' to a narrow 1.5' because the surrounding grass grew over, coming up between cracks and then simply growing on top of the stones. I sprayed the whole path with an Eco-friendly, non-selective herbicide (essentially a very strong vinegar solution) and cut out the resulting dead (& already returning! grass).
My plan is to sweep & pack down sand between the cracks, then try to better stay on top of grass as it emerges. Given the stage I'm at though, I wonder if there's another preventative course of action to actually further prevent the encroaching grass and weeds (it was mainly just lawn grass I had growing there, not so much typical weeds).
**I am NOT prepared to pull up the stones, lay landscaping material or cement, and re-set the stones.