Yes, You should need to change them from time to time, but I believe using worms shall keep them clean and healthy plants.
I am using currently red soil and never changed for any plant in life because it may die.
What you posted is correct as we need get rid of these fertilizers and other dust from time to time. Although while doing this no one knows if the plant live again or not.
I think you are using normal plants can you confirm does they bear fruits or vegetables? I have seen where the plants bear fruits must need a fresh compost all the time to bear huge fruits or vegetables.
Tilling 25% and refilling with leaves or some organic compost is excellent method as for me.