How do I renew my AppleCare plan?

If you are referring to AppleCare+, you have 30 days from the date of expiration to renew it. If you are referring to the standard one year AppleCare plan which came with your iPhone, that cannot be extended.

See this link for help --> Extend your AppleCare+ coverage - Apple Support

If your within the eligible period to renew your Apple Care you can renew your coverage. If you’re in the US please call  1-800-MY-APPLE or outside the US, consult the support articles below.

Contact Apple for support and service - Apple Support

"How do I renew my AppleCare plan?: Apple care expired want to renew"

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Confirming AppleCare Coverage:

Sometimes, it auto-renews. So, see if you already have had it renewed...

A. Enter the Serial Number here: Check Your Service and Support Coverage - Apple Support. Click on the iPhone, and see what it says.

B. Where to Obtain the Serial Number:

• Original Packaging
• Purchase Transcript
• On the iPhone itself:

Already answered, in the first reply in this thread.

Renew Apple care