Is it the universal sonar cable? If it is it is very easy to change. There is a connection underneath the terrova head that unscrews and you just replace it with a new one.
I also managed to cut mine—got ahold of the replacement part and fixed myself–you will have to remove 3 screws to open the head but very easy to replace.
I followed trumars instructions and it is still working great after 2 seasons print it off and keep it some place where you can find it for the future. I have learned to keep an eye on how many times the cable gets wrapped around the motor.