Get you a TDS tester and measure the amount of nutes in the soil. In my hydro system the ideal range is 800-1200 ppm of the nutes. I like to keep mine more towards 800 and increase towards 1200 in the flowering stage when they need the extra nutes for budding.
It it were a batch of good seeds, I would resoil. If you don't have much involved at this point, then starting over would be the way to go I think.
Even if you flush the grow pot, you will still have a high nute level because the osmocote is time released. That problem won't go away until you change soil.