You could try shaving the bill, but I'd be afraid of messing up the action entirely. Each plug is different, especially in regards to buoyancy. Your best bet is keeping that one as a subsurface plug, and picking up another one that will hopefully stay on top better. I went through a couple slammers before I found one that really stayed on top at an almost fast retrieve, and it was worth it, those ones are often the best.
-Brian