Second grow in same pot - Remove old root ...OR?

What should I do when I harvest with the root. Do I just cut the plant down to the soil and leave the old root to break down or will that rot and cause issues when I replant? I'm unsure if I should dump the pots and remove the old roots and replace the soil. In the wild I know that the old roots have time to break down over the winter and there are other forces acting to maintain balance. Confused here. Any help from those w/ experience would be appreciated.

I cut off to the base of the plant. Dump all the soil and roots into my compost pile.

If you're going to reuse the soil remove all organic materials. Allow to dry thoroughly.

What are suggested things to do to soil when prepping for a second grow? Add compost or ? flush with straight water and add seedling and start all over adding nutes week 3 or 4 ?