I started with 5 gallons of Apple cider and 1/4 cup of brown sugar using Lavlin yeast and a starting SG of 1.050. It has been six days and I have not done anything else yet, bubbling about every 10 min still. Upon reading further I realized that the ABV will not be as high as I thought. It is too late or can I open up bucket during this fermentation and add more sugar or honey to increase the ABV at the end or is it too late?