Depending on your setup, you can do water slow, frequent water changes. All of my shrimp tanks are on a system where the tap water goes through a house filter, then into two 44gal Rubbermaid garbage cans. The water in the cans has large airstones and heaters (for the winter months). Early this summer we had a surprise 95+ weekend and our A/C died the day before! Even though the shrimp were in the basement, all the tanks jumped to 83 degrees. I basically drained the stored water, let the cold tap water refill (~73 degrees off the street) and let the impurities and chlorine filter out. By the end of the last day of the heat wave I was able to keep the temps to around 76 degrees. The next day the A/C was fixed. In the end I only lost 1 berried CRS (of course) and a berried Blue Pearl.. the rest of masses of shrimp were spared.
Obviously this isn't a solution for most, but perhaps can give some other options for all of you living in the heat.