Take the shoelaces and cut them so they have about half an inch or a little less of the lace still attached. If need be cut part of the hard tip off to make it easier to shove a needle through. Then take a needle, I used needles with broken eyes, and push it from the frayed end of the shoelace tip through the part covered in plastic until the point sticks out the front and the back is completely covered. It helps if you use needle nosed pliers to pull on the tip of the needle when it becomes visible.
I have seen these on many instructables and other sites. I do not know where I first saw them so I am not giving credit to any individual person.