I would remove the top layer of moss(?) and put some new compost on it. Be careful not to chop into its roots and keep it watered and in a sheltered spot. It looks to be in very good condition. I had a very difficult time changing a terracotta pot on a camellia which had only been in the original for 18 months, after it had flowered. The fine roots must have penetrated the pot and even going around the edge with a bread saw didn't release it! I still have the scars! Perhaps waiting until autumn might be easier. It's in a good deep pot and you will need to find one as deep or deeper. Have you thought of planting it in the ground?