If your tomatoes are indeterminate, you can cut them back a bit take off poor looking leaves, and they will take on new life.
Determinate tomatoes are pretty much done and you have to succession plant those, in order to have production through the entire season.
If I have this right-
determinant are the shorter bushy ones like our Early Girls-They are still producing and have been for two months. I thought they produced all at one time, but I was wrong.
indeterminate, the long viney ones that were 9ft tall have fell over and not doing as well with their stems pinched. These are thew ones that I want to trim off very short and have them grow back a second time. They were our tasty slicers, hybrids and heirlooms, that were 5in diameter and so tasty. That sound like a viable plan?