You can, access router via SSH and enter command below:
gsmctl -A AT+CPIN=\"PUK\",\"PIN\"
* PUK - change this with your SIM PUK.
* PIN - You could enter your old PIN or change to a new one.
P.S. you must enable the card. It won't work if you have 2 cards and card number 2 is active, although you want to change the PIN on card number 1.