Unlike horses and ponies, beagles don't have separate names based on height. Whether a beagle stands under 13 inches or between 13 and 15 inches at the shoulder, it's still simply a beagle.
Breed standards may recognize two size varieties, but both fall under the same breed name. There is no distinct "taller beagle" with its own title—just beagles of different sizes within the established range.