I have a self started three year old avocado tree in a five gallon pot which is wind beaten. I am moving next year and want to plant it there. I think it needs nourishment and care. Can I take it out carefully,add new soil and put back in same pot?
Sure you can do that. If you want to refresh the soil, the best thing is to remove as much as possible soil from between the roots. When there are too many roots, you'll probably need a larger container or you can prune/trim the roots off. However, doing a root trim, the plant above the ground needs to be trimmed/pruned as well. Be aware that the best time of the year to do this is early spring.