I like to add 1/2 - 1 C DME (dried malt) when I make hard lemonade. I also use a yeast starter because it's hard to start a ferment with lemonade. I also use yeast nutrient in the starter, for the same reason.
Good luck - hope you like it.
Ageing: Apfelwein, Lodi Ranch 11, Plum, White Zin, Tomato, cider
Drinking: Cab, Rhubarb, Rhubarb Grape