Yeast don't die at low temps, they just "hybernate."
Once you get back to proper fermentation temps, you can just gently swirl your wort to resuspend the yeast, and they will get a whiff of the available sugars and come right out of hybernation to feed and reproduce!! Just gently swirl, don't do it briskly enough to introduce oxygen, and you'll be all good.
Primary #1 - Midnight Ryeder (Midnight Wheat and Rye)
Primary #2 - Florida Weiss
Primary #3 - Kane-DOH APA (Honey Citra APA)
Secondary #1 - Downtown Flanders Brown (brewed August 2012)
Keg #1 - Raspberry Florida Weiss
Keg #2 - Cinnamon Raisin Cider
Keg #3 - NONE!
Bottled - NONE!