I was told the same thing in March 2012 at the airport ICE booth. I have my plastic credit card sized piece that contained the SIM card, ID #, PIN #, and PUK #. I also have my receipt.
You can reload the SIM card here.
https://apps.grupoice.com/VEPPlusWeb/RecargaPrePagoMovilFormController.spThis may seem obvious to most but due to their strict no-refund policy, I wanted to clarify one item. If you follow the link above and enter your CR phone #, it wants you to enter "TOTAL". It does not specify if Total means Colones, Minutes, or US Dollars. The last thing I want to do is add $5,000 in credits (or 5,000 minutes) when I'm trying to add 5,000 colones.
{edit}
The above link is suddenly acting up for me. I don't know if they suddenly blocked my IP address or if they are down for maintenance.
I found it by using the following steps.
Using Google Chrome (since it translates the page into English)...
Go to
http://www.grupoice.com/wps/portal/kolbi_prepago_kitsFrom the menu select
Prepaid Kolbi, then
Reloads, then
Recharge Online HereEnter your phone number
It will tell you your name
You then select the Total amount you want to add to the card (in Colones)
Agree to Terms & enter your Visa or Mastercard info.