In a pot, add water, agave nectar, and white sugar.
Place the pot on the stove and bring the mixture to a boil. Stir well until the sugar is completely dissolved. Let it boil for about 5 minutes while stirring occasionally.
Remove the saucepan from heat and allow the sweetener mixture to cool. This may take some time.
While the mixture is cooling, cut 5-6 lemons in half. Squeeze the lemons to extract their juice. You'll need about 1 cup of lemon juice.
Once the sweetener mixture has cooled down, pour it into a pitcher.
Pour the 1 cup of freshly squeezed lemon juice into the pitcher.
Fill up the rest of the pitcher with water to your desired level. You can add ice cubes if you like your lemonade extra cold.
Stir the lemonade thoroughly to ensure all the ingredients are well combined.
Take a sip to see if it tastes just like Panera Bread's lemonade. Adjust the sweetness or tartness by adding more water or lemon juice if needed.
Pour your homemade Panera Bread lemonade into glasses filled with ice cubes.
Enjoy your refreshing lemonade!