Charles Ellicott Commentary Leviticus 13:57

"and if it appear still in the garment, either in the warp, or in the woof, or in anything of skin, it is breaking out: thou shalt burn that wherein the plague is with fire." — Leviticus 13:57 (ASV)

And if it appear still. —If, after the affected piece has been cut out and burned, the affliction appears again in another part of the garment or skin, it indicates beyond doubt that it is spreading leprosy; the garment must therefore be entirely destroyed, as this disorder is incurable in fabrics.