The blintzes have a better texture if the batter rests for half an hour at room temperature. You can also let the filling chill for half an hour in the refrigerator. If the batter gets too thick while it is sitting, you can thin it with a little bit of cold water.
Uncooked blintzes can be frozen individually on a tray, then wrapped individually and frozen for up to 3 months. The cooked blintzes can be refrigerated for up to 1 day; they can be frozen, using the method for uncooked blintzes.
To reheat, just place in a pan with butter and fry until it’s warmed or microwave for 20 seconds on high. Serve alone, with topping such as blueberry or apple filling or dust with confectioner’s sugar.