Answer: Bay trees seem to do well in relatively small containers, so do not rush to repot it. In the meantime you can refresh the top few inches of soil by replacing it with fresh soil each spring. If you need to repot, do so in the early spring. Or, consider root pruning lightly and repotting into the same pot with some fresh soil added. This will limit its growth somewhat so you would try this technique when it is as large as you wish it to be. Use a potting mix similar to the one it is already growing in. In any case it should be a good quality free draining mix formulated for container plants.
Aphids can be treated with commercially formulated insecticidal soap, apply and reapply per the label directions. You can also remove aphids with a strong spray of water from the garden hose if the plant is outside. If you plan to use the bay leaves in cooking you would never use a systemic on the plant. And, be sure any product you use is listed for indoor use since you will be bringing it indoors.
Also be sure you are not overfertilizing your plant as excessive nitrogen can encourage extra fast foliage growth which in turn can be especially attractive to aphids.
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