Glucose tabs. Generally, any food/drink with fast acting carbs like juices, glucose tabs/gel, candy in right amount would bring up the blood sugar. Its important to recheck the blood sugar level in 15 minutes and retreat if necessary. Depending on the condition causing low sugar, you should have a contingency plan formulated with your doctor.
Hard candy. Cake icing, sugar tablets are other options. If you are an Insulin pumper, remember to suspend Insulin! Peristent hypoglycemia can also be treated with mini glucagon doses (check with your endocrinologist/cde about how to go about the latter option).