I have actually used a small shovel and slipped it in and under the plant and lifted it out along with the surrounding soil and set it off to the side. Covered it with a moist dish towel to minimize light exposure. Quickly remove the oldSoil to your satisfaction. Add a new soil to the bottom of the pot kind of eyeballing how hi you’re going to want the plant to sit in the pot.. remember it will settle so you might want to go a little high. I am a fan of shaking or knocking off most of the old dirt from the roots but I know there are people who will argue that point to the death. If you have two people one can holdOne can hold the plant in place while you backfill or if you have to you can hold it and backfill with a trowelOr your freehand. Now, this may not work if the pot is root bound. It may cost too much damage. Transplanting isn’t rocket science. You just have to plan it and get her done as quickly as possible. Have it all set up. And have your new soil conditioned with Moisture before you get started. I don’t know if you have any mycos , But if you do use it. I have been successful a few times using this method with small root balls.