That's getting into the low end of keeping the yeast active from my experience. Is the airlock still bubbling? If not then you'll need to move your primary to a warmer spot in your residence to get the yeast going again. Once you move it you can give your primary a slight, and I mean SLIGHT, stir to get the yeast kicked up to get it active again. I just did the same recipe, Bavarian Hefeweizen Extract, and mine had active fermentation for 6 to 7 days at 66 to 70 degrees. Temperature control is the biggest factor in home brewing next to sanitation. You do well in those two areas and you'll usually make good beer.
Sheepdog Brewing Co.