Well you would either have to re-crimp or solder. If the existing plug is a solder type, it is just a simple clean the ends of the wire and resolder. If the connector is a crimp type, then you would have to prep the wire end with stripping some of the insulation, get a new crimpable connector and redo the connection that way. Just be aware with cutting/stipping one of the wires will shorten it compared to the other, so you may have to do it to the other end as well.
This is provided that you have the tools to do the job properly (crimper/solder station), or know of someone that can do it for you, otherwise, it is almost easier to just get a new cable.