Replacement certificates can only be sent out to you from the Lifesaving Society directly. You need to contact them and request for a replacement certificate to be sent to your address.
Alternatively, you can pull up all of your certifications by looking up your LSS ID on find a member and use that as proof of your certifications.
Your LSS ID is composed of 6 letters/digits and can be found on the bottom right corner of any lifesaving society certifications.