Combine apple juice, quinoa, and vanilla extract in a large pot; bring to a boil. Reduce heat to medium-low, cover, and simmer until quinoa is tender and liquid is absorbed, about 15 minutes.
Gently fold blueberries into hot quinoa. Pour blueberry mixture into a 9x13-inch baking dish. Cool until quinoa is set.
Whisk almond milk, water, and cornstarch together in a small saucepan over high heat. Add lemon juice and maple syrup; cook, stirring constantly, until glaze is thick, 2 to 3 minutes. Pour hot glaze over quinoa to cover it completely. Cool to room temperature. Cover baking dish with plastic wrap and refrigerate for at least 2 hours.
