Yes! You have a couple options:
You can enable overage hours, which will allow you to continue to check in at a rate of $6/hour (or equivalent currency). Head to your Account Settings to activate this option, and then just check in as you would normally. After you check out, your payment method on file will be billed for any overage.
You can also upgrade seamlessly to a higher membership tier from your Account Settings. When you upgrade, your Croissant membership will immediately start a new monthly cycle with the new plan.
You can also buy one-off packs of hours in your account settings as well.