I don't think it is a good idea to kill your whole lawn and start over.

The problem is that eventually weeds like crabgrass are going to come back.

Controlling lawn weeds are a year-round, continuous program of keeping a healthy lawn, using a pre-emergent chemical to prevent this stuff from germinating, killing them as they grow, and then re-seeding in the spring and / or early fall to limit the amount of space where weeds can grow.

At the end of the day the only way to prevent crabgrass is asphalt or cement.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".