If your parents have not gone back to their home country since the PCC was issued then they don't need a new one.
Just send the previous one with a brief letter explaining that they haven't returned to their country.
All the best.
Hi victorknow,
Yes you can submit the pcc that you already submitted that's what we did. We wrote a brief letter explaining that we haven't been back since and that we were told that we could continue using the same pcc.