I have re-potted citrus trees in every month of the year, and I am in Colorado with weather much worse than Arizona. The word for repotting is "CAREFUL". In Oscar Tintori's book, Oscar writes about the century old containerized citrus trees of Tuscany that are transplanted every 2 or 3 years without ever taking the trees out of the container. This is done by using a long knife and removing 2 inches of the tree's root ball on all four sides, followed by refilling the void with new medium. These 100 year old trees have been re-potted by this method 25+ times, and are still living to this day in great condition. You see, there is more than one way to skin a cat. Do what ever method you wish to do CAREFULLY. I would do as FMfruitforrest writes, and first check if your tree has root rot. Best to you and your tree.