I am sorry for this delayed reply to your gardening question. The spring rush has brought a deluge of questions and we are working hard to catch up!
You don't need to replace the soil. It is corn gluten meal not corn meal (they are different) that inhibits germination of some seeds. Even that product doesn't last that long and in a month or so won't be inhibiting seeds any longer.
Thanks for the question. Best wishes for a wonderful gardening season. Please stop in again soon!
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