Answer: Unfortunately, if you used a nonselective herbicide such as one containing glyphosate, then you will need to start over.
Please check the label of whatever product you used to verify if there is a waiting period before replanting an area where it has been used.
Also, keep in mind that the poison ivy may regenerate from the roots. If so, you may want to spot treat the regrowth by applying the herbicide with a wipe on application method rather than spraying it so you have better control.
Here is some information about starting a new lawn or renovating a lawn you may find useful. You may need to cut and paste the complete url into your browser to make it work correctly.
Good luck wiht your project!
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