Begin by pouring the white wine, vodka, and sugar into a large pitcher. Stir the mixture thoroughly until the sugar has completely dissolved.
Incorporate the fresh strawberries and blueberries into the pitcher. Place the pitcher in the refrigerator to chill until you're ready to serve.
Just before serving, add the lemon-lime soda to the pitcher. This step ensures that the sangria retains its effervescence and refreshing bubbles.