Select a Payment Information type (Credit/Debit card or Net Banking) and enter your bank information. Click Re-subscribe.
Select Switch to monthly billing.
Click Switch, then Done.
The charge for the 1-month renewal will offset the charge for the annual billing cycle when you do the switch. You will also get an email to confirm the charge. Please visit this article for further details : How to re-subscribe or reactivate QuickBooks Online
For additional resources, these articles provide an overview about managing your QBO accounts. From there, you’ll see the complete steps on how to reactivate a subscription.