Payments can be skipped from the upcoming payments tab of a membership:
Note. Payments will also be skipped if a membership is on hold, after the payment date has been succeeded.
To unskip a payment:
Go to Customer List and select customer.
Go to Plans and Packs and select relevant membership. From here you will see there is a 'Skipped Payments' tab, click on this.
You will now see the option to Unskip, next to any skipped payments: