If the crack is at the weld, maybe the blade could be rewelded, in hopes that it was just a bad weld to begin with. However, if there are several random cracks on each blade, this means it has reached the end of its metal fatigue life and should likely be discarded as it is worn out.
Bandsaw blade resistance welders can be bought to buttweld blades. Fairly expensive for a few blades, and still takes a little bit of art to do a good weld. Other guys have silversoldered blades, but that is another art to be learned.
First you get good, then you get fast. Then grouchiness sets in.
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)