There are several things you can do:
1. Brownell's makes a product called cable fix, also saw something called servicing saver, but I have to admit I have not tried them as I make and serve my own.
2. Learn how to serve. It's not that hard. Lots' of info out on the net, even videos.
DO NOT keep shooting with separated or worn serving. It can cause the string to wear and weaken leading to a potential string failure.