That's encouraging that it's getting sharper, that would seem to indicate that your bevel is in good shape. However, black arkansas stones are very very slow so you may need a few hundred more laps to sharpen it fully. Once it's completely sharp then don't ever let it get dull, as soon as you notice it losing some of its sharpness then you should give the razor another 10 or 20 laps on the arkansas.