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 - EMPTY!
Secondary #1 - Downtown Flanders Brown (brewed August 2012)
Keg #1 - Pina Colada Florida Weiss (smoked Pineapple and Coconut Berliner)
Keg #2 - Cinnamon Raisin Cider
Keg #3 - NONE!
Bottled - NONE!