Necklace extender

On Christmas my daughters got a necklace from one of their cousin, they were nice necklace and my daughter keeps wearing them until one of the necklace was broken. It was their first necklace so I am trying to find a necklace extender to repair the necklace. I put the necklace up until now I still can not find an extender I am just too busy here with other things and forgot all about it. It is just good that my daughter never asked about them but they are still waiting for me to fix them.