When you re-pot a plant that has been in the same pot for many years you want to trim the root ball. Repot when it is dormant, usually Jan. is the best time. Get a sharp knife, take the plant out and hack off a couple of inches off the sides and bottom of the root ball. YOu want to reduce the root ball to 3/4 of its original rootball size. If you are putting it in the same pot, add new soil on the bottom of the pot and on the sides.