One has to weigh the cost of repair against the value of the object.
If the dish has a stable crack, then you might consider leaving it as-is. I have heard of repairs to glass which can minimize the appearance of the crack but it does depend on the color of the glass, thickness, and location. And most importantly, such work is expensive, as in several hundred dollars or more.
If you are eager to move ahead with a repair, search online for a "glass conservator"