Kettle Fire

After a significant kettle fire, is it recommended to drain the residual asphalt (type IV), and replace with new asphalt?

Jed, back in 1975 I hired a guy with a tiny old kettle (no thermostats in those old ones) to do a little one-square patch. I helped him get situated and offered to set roll for him. While we were heating up the kettle caught on fire and I went running to get a cup of water. Didn't take long and when I got back to the kettle the fire was out. I asked him where he got the water and he didn't reply at first so I pressed him on it. "Ah used some o' ma own."

What do you mean by "significant?" Did the kettle get run down too low?