Turn the rug so the underside is facing up. Thread a needle with button or linen thread. Button and linen thread are stronger threads. Tie a knot at the thread end. Use thread in the dominant color of the rug.
Start at the inner most disconnected braid row. Grasp the separated braid's side. Hold it against the braid next to it. Pin the braids together to hold in place while you sew. According to Capel Rugs, position your needle before the separation between braids begins. Start sewing about 1 inch from the gap.
Insert the needle at the left end of the separation. Sew through the top half of the braid using a whipstitch, connecting one braid to the next, beginning by pulling the needle until the knot touches the braid.
Insert the needle through the top half of the braid beside the first braid. Pull the needle until the thread tightens the braids together. Cross the needle over the braids and back to the spot of the initial stitch. Move the needle over ¼ inch to the right. Insert it through, repeating the stitches until the separation is closed. According to Capel Rugs, sew past the separation, by about 1 inch.
Sew two stitches through the fabric to secure. Remove pins.
Use a seam ripper to remove stitches impeding rebraiding. Sometimes you have to unbraid further than the loose place in order to create a tight braid.
Unbraid the braid. Some rugs are not made of continuous braids, but of varying lengths of braids sewn together at the ends. Salvage the braids not in need of rebraiding by locating their connecting points and using the seam ripper to cut those stitches. Set aside the undamaged braids until time to reconnect the braids and reassemble the rug.
Rebraid the strips tightly. According to Fix It Club website, in the article, "Rug Repair," sometimes it's necessary to replace damaged fabric strips before a braid can be accomplished. If this is the case, see Section 3 on restoring damaged braids. Sew through the braid ends to connect the strips to form one long braid.
Recoil the rug. Pin the braid to the braid beside it. Follow reconnecting instructions in Section 1.
Use a seam ripper to remove the stitches connecting the damaged braids together. Remove the stitches to the point of the damage origination.
Unbraid the braid. Salvage the braids not in need of repair by locating their connecting point and using the seam ripper to cut those stitches. Set aside the undamaged braids until time to reassemble the rug.
Cut away the damaged fabric strip. Use similar fabric to replace the strip removed. Cut a replacement strip according to the width of the strip removed. According to Braided Area Rugs Club website, in the article, "Fixing the Braided Area Rugs," if you cannot find similar fabric, remove the stitches connecting the outermost rug braid. Use the fabric from this braid. This will slightly reduce the size of your rug, but the fabric will be a match.
Sew the replacement strip to the end of the strip from which you cut away the damaged fabric. Braid the strips, keeping the braid tight. Coil the braid, replicating the previous pattern. Pin the fabric of the braid tops together.
Whipstitch the braids together on each side of the braid. Turn the ends of the last braid coil under and sew to the braid to finish the rug's last row.