The most common remedy is to make sure the meringue topping is sealed to the crust before baking it. But in my experience, that doesn't solve the problem. For the next cream pie I make, I plan to try these ideas from
America's Test Kitchen. They say that the filling must be very hot before the meringue is spread onto it, and that a cornstarch "slurry" will help prevent weeping.
MERINGUE TOPPING1 tablespoon cornstarch
1/4 teaspoon cream of tartar
1/3 cup water
1/2 cup sugar
4 large egg whites
1/2 teaspoon vanilla extract
After cooking the pie filling until thick, remove it from the heat and place plastic wrap directly on the surface of filling to keep it hot and to prevent skin from forming while mixing the meringue topping.
For the meringue topping, mix cornstarch with 1/3 cup water in small saucepan; bring to simmer, whisking occasionally at beginning and more frequently as mixture thickens. When mixture starts to simmer and turn translucent, remove from heat. Let cool while beating egg whites.
Heat oven to 325 degrees.
Mix cream of tartar and sugar together. Beat egg whites and vanilla until frothy. Beat in sugar mixture, 1 tablespoon at a time; until sugar is incorporated and mixture forms soft peaks.
Add cornstarch mixture, 1 tablespoon at a time; continue to beat meringue to stiff peaks.
Remove plastic from filling and return to very low heat during last minute or so of beating meringue (to ensure filling is hot).
Pour filling into pie shell. Using a rubber spatula, immediately distribute meringue evenly around edge then center of pie to keep it from sinking into filling. Make sure meringue attaches to pie crust to prevent shrinking. Use spoon to create peaks all over meringue.
Bake pie until meringue is golden brown, about 20 minutes. Transfer to wire rack and cool to room temperature. Serve.