Adding a Suica Commuter card to Apple Pay is just as easy as a regular Suica. You can also renew the commuter plan right in Wallet without a trip to Suica App. However one thing you need to be careful of is the Commute Plan renewal window.
Suica commuter plans are good for 1-3-6 month renewable periods that you choose when renewing the plan in Wallet. You can only renew a commuter plan 14 days before the expiration date. If you go past the expiration date and miss the renewal window you can no longer renew the commute plan in Wallet. Another Wallet limitation is that you cannot change the commute route of the commute plan. Both require the Suica App and a Mobile Suica ID.
To renew a commute plan past the expiration date use Suica App and be signed in with your Mobile Suica ID. In Suica App purchase a “new” commute plan. Follow the screens below, tap Commuter Plan > New > Renew Plan from previous route > choose 1-3-6 month validity and start date. The last step is purchase with Apple Pay. You can also charge the commuter route plan if necessary.
Once complete your Apple Pay Suica Commute Plan is ready to go. It is not a new Suica card, it is the same Suica card with a new Commute Plan and validity period.
Update: see All About Suica App Commute Plan Renewal for up to date Suica App information.