Sorry to be so slow...
You could pop the bubbles and refire them. You can use much the same schedule that you did previously, just skip the long hold at 200°F. Then visually confirm that the bubbles have closed by monitoring the casting at top temperature. Generally speaking, you want to monitor castings at temperature to make sure that you keep an eye on any bubbles that might be coming up, and either skip before they disturb the surface, or commit to holding at temperature long enough for them to pop and heal.
I hope that this helps.