For a stronger lemon flavor, consider zesting one of the lemons and adding the zest to the pink lemonade while heating. If you don't have lemon vodka, you can substitute with plain vodka and a tablespoon of lemon juice. To easily slice the jello shots, dip the knife in warm water between each cut. These jello shots can be made a day in advance. Store them covered in the refrigerator to prevent them from drying out.