You mean burned from turning it too fast? You could just grind the bit back to good steel.
And, if you're willing grind it by hand you could get a 3/16" square highspeed tool bit from any industrial tool supply place. You might be stuck with this alternative because even though they say the bit is replaceable, they might not make the bit.
Just be careful hand grinding on a pedestal grinder, you might not think so, but a lot of people lose fingers using one.