Yes, this is possible. 

Once they are in their portal account, they can update their Card details by selecting the 'Edit' option from under the Payment Method Information (V1)/ Payment Methods(V2) section in the portal. Screenshots below. 

Customer Portal V1

Customer Portal V2

If you're not using the Customer Portal, you can also email customers with a secure link asking them to update their payment details. This can be done using the Request Payment Method option on the customer details page. 

Here's more on that.