First, you can monitor who has overdue payments from 3 places:
Dashboard - Failed Billing section
Overdue payments tab on Payments report
Individual member detail page
How to Collect Payment
From either the plan modifier dropdown on member detail page or Invoices tab, click on the menu to reveal "view invoice". From there, you can select what payment method and amount to pay against the invoice.
If someone has updated their credit card for payment:
Verify that the billing method the plan is trying to collect on is the same as the new card added (on member detail page)
Alternatively, you can just wait for the nightly batch to run it. As long as the member has updated their billing information to a valid form, the system will reattempt to collect payment.