Remove the agave plant from its old container. Gently shake to remove any old dirt remaining on the roots.
Remove any pups, or offset plants from the base of the agave plant. These are easy to identify, as they will be small plants growing separate from the main plant. Use a sharp knife to slice these away from the root.
Place the pups and the original plant, cut side up, on newspaper and allow to dry, or heal over, for several days. If you did not remove any pups from the plant, continue to the next step.
Combine equal amounts of potting soil, sphagnum moss and sand in a bucket and stir with your hands to distribute the ingredients evenly.
Fill the new growing container with the soil mixture. Scoop out a hole in the center just large enough for the root ball of the agave plant.
Place the root ball in the hole, spread the roots out evenly and cover with additional soil mixture.
Water the repotted plant after the soil mixture feels completely dry to the touch.