Melt 1 tablespoon of the butter in a 12-inch skillet over medium-high heat. Add the onion, juniper berries, bay leaves, and 1/4 teaspoon salt and cook, stirring frequently, until onion is softened, 3 to 5 minutes. Stir in sauerkraut, apple, bacon, brown sugar, and broth, increase the heat to medium-high, and bring to a simmer. Reduce to medium-low and continue to simmer until the liquid is almost evaporated, about 20 minutes. Remove the bacon and bay leaves, stir in the remaining tablespoon of butter, and season with salt and pepper to taste.