I'm not sure what type of dies you have, but in most (probably all) you can replace the decapping pin.
If you unscrew the central stem of the die from the die body and then unscrew the collet that holds the pin in place the broken end will come out and you can replace it with a new one. The Redding dies that I use come with a spare pin in the box. Other brands might do also.
Cheers,
Bob