Answer: A straight tramnsplant is fine as long as the old potting soil doesn't have an insect or diseases in it. A general rule when replanting is to increase the pot size about 1 inch in diameter. If the plant was not root bound, you may have not needed to repot. The logic behind the rule is this: when the pot size is increased, the amount of soil is increased as well as the amount of water retained by that amount of soil. If too much soil is added, then too much water is retained. Thus there is a chance for root rot. Retaining the soil when repotting is a good idea...less shock (loss of those all important and very fragile root hairs). It doesn't hurt, however, to do a little root pruning to stimulate new root growth..
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