We purchased a Navigo Pass in Paris in 2013. We are returning in May 2020 and are wondering if we can just reload this pass with additional money or do we need to purchase a new pass.
Navigo cards from 2013 should still work for reloading at ticket vending machines (or ticket windows). Navigo passes are supposed to last ten years from date of purchase. But there was a change in cards that happened in 2014 and again in 2018 so there's a possibility the card no longer is recognized.
You can test your Navigo card at any ticket vending machine with a light blue or purple Navigo card reader. Just place your Navigo card on the reader and see if the machine recognizes it is there. If the ticket machine offers the option of reloading a week or day pass, then the card can be reused.