I have some 10 year old Durana plots in middle Georgia. They will sometimes get crispy brown in the summer drought, but always bounce back in the fall, when cooler weather and a little rain comes in. You're farther north so you could overseed your plots with Durana and maybe Patriot clover (both Pennington seed) and give that a try, this fall.
I have Durana and VNS Ladino, they will both go dormant in drought conditions but both come back when cooler temps and the rain starts in the fall. I am actually thinking about planting alfalfa and chicory to see if they will withstand drought conditions.
I've got 2 WI alfarack plots look great but they get bailed up once a year and the clover plots are in areas that can't be reached by bigger equipment. We've had some rain and one of the 2 clover plots still looks completely dead so not sure if the heat/dry weather didn'tfinish it off.
This year I planted aberlasting white clover for the first time. Did some research and it seems to be a decent clover to plant. Drought resistant and fast rebound from grazing. I bought it from welter seed and honey. Planted it with other clovers, chicory, sanfoin and an oat cover crop. Everything seems to be coming up great. I think the aberlasting clover is worth looking into.
^^^^This. And throw in chicory and your set for the dry days. My clover looks overbrowsed and poor at moment but alfalfa still growing and chicory is everywhere whether I planted it or not. Good carry over for the heat of Aug then clovers will bounce back.
Alfalfa, chicory, and even birdsfoot trefoil once established .... are more drought tolerant than clovers. In a mix these plants act like plot drought insurance, but with adequate rain or cooler fall temperatures clovers can bounce back and dominate. https://www.grandparayoutdoors.com/product-page/3x