We will need to re-fill our Navigo Decouverte Passes, as we will be in Paris longer than the Sunday night expiration. Can we re-fill them at a Metro station in Paris, perhaps in the 4th arrondissment?
Thank you! Your "Paris Navigo Decouvert Pass - What You Need to Know" was so, so very helpful!
If you're planning to stay for several more days after Sunday, then yes, you will need to refill your Navigo Decouverte passes. Note that you can refill your Navigo anytime after Thursday midnight for the following week. Any week-pass refill made after Thursday midnight will be for the next Monday to Sunday usage period.
You can make the refill at any Paris Metro, RER or Transilien automated ticket vending machine with a Navigo card reader (purple or blue colored area which you place your card against, some photo examples of Paris Metro/RER ticket vending machines). Any of the Metro stations in the 4th arrondissement should have ticket vending machines to do this. You can also ask the ticket window agent in the Metro station to refill/recharge your pass as well.
Thanks for the kind words about the Navigo - what you need to know article.