Grasp the cactus firmly through several levels of newspaper or gloves. Tip a cactus that has been potted to make removal easier. Check the bottom of the cactus for damage or insects. Wash as much of the old soil off of the roots if there are more than a few mealy bugs.
Line the bottom of a wide, shallow pot with broken pot shards or gravel to provide drainage for the cactus. Fill the bottom of the pot with a cactus soil mixture so the crown of the cactus sits evenly with the top of the pot.
Place the cactus in the new pot, packing soil around it until it can stand on its own. Gently tuck soil into the spaces between the pot and the cactus without packing it tightly. Wait two weeks to water the cactus so it can recover.