Brennanowhere

Hi all! My parter and i are sailing on the ovation in March and we don't want to attach a credit card to our sea pass cards as the last cruise i went on it went pear shaped. How do we add money onto our seapass card? Can we add more throughout the journey? Can we keep track of what we have spent? This may seem like a silly question but I've only ever sailed when i was under 18/21 so i didn't have all of these descisions to make by myself!! Any help is much appreciated!