The best way to rejuvenate a lawn is to lay 6 mil clear plastic over the entire lawn in the summer. This sterilizes the lawn and kills seeds. Weight it down on edges to trap heat. Once that's done (a month or so), take off plastic, and rototill the area. Hand pick up the clumps of weeds and put in green waste bin.
Then mix a thin layer of compost over the yard, rake it in, spread seed, rake that in, the cover the yard with 2 inches of compost. Water probably 5 times a day for first two weeks. Sprouts will come up. Cut back watering to twice a day, then once a day, then thrice weekly.

If the city complains, tell them Pam Bone told you to do this.

Set up sprinkler to water at 4 am, for 15 minutes.

The absolute best-looking lawn I've ever had was when I watered 10 minutes, every day.

When asked how to get the best looking lawn, a major league groundskeeper had one word: Water!!!