The sparkling beverage has seen its stock cut almost in half since peaking in March. Better days could be coming.Not every stock has participated in the summertime rally. Celsius Holdings (CELH -0.60%) has fallen sharply, shedding nearly half of its value since hitting an all-time high in March. The company behind the now widely available functional beverages that help drinkers burn fat and calories when accompanied by cardio activity has lost its carbonation. Is the fizz gone forever?Two analysts this week ...