My plants are drying out and withering, so there is no expectation of continued production. If they are still green and producing flowers, you should be able to coax something out of them.
Phosphorous is a good bet. When I plant tomatoes, I dig a hole, drop in a handfull of 3% rock phosphorous, then bury the plant up to it's crown. For other veggies, I broadcast the 3% rock phosphorous and water it in by hand.
What is your soil like? Are you using raised beds?
Using 4x4 with Mel’s mix in one box and my own mixture in the other. I am going to rip up the one with my own mix, add some phosphorous and some other goodies and replant.
See what happens.