It is much better to freeze a fruit pie before baking than after – the texture suffers substantially if frozen after cooking. If you must, thaw it at room temperature for about three hours, and then crisp it in a 450°F (235°C) oven for about 20 minutes.
If you can freeze the pie before baking it, don’t defrost it when the time comes. Bake it unwrapped at 425°F (220°C) for 15 to 20 minutes, then lower the temperature to 350°F (175°C) for the remainder of the cooking time. The total baking time will be about 20 minutes longer than for an unfrozen pie.