Hello Tessa,
If you're still having issues with the Apple Watch not updating, next you'll want to confirm that Set Automatically is enabled in Settings > General > Date & Time on your companion iPhone, and that the date, time, and time zone are shown correctly.
If the issue continues after enabling Set Automatically, or the date, time, and time zone are shown correctly make sure that any VPN or security software is temporarily disabled. If the issue persists at that point please go in to Settings > General > iPhone Storage on your iPhone, and verify that the watchOS update doesn't appear in the list of apps. If an update appears please swipe across the update, and tap delete. Then attempt to update again.
Next you'll want to reset the Apple Watch as provided in the section How to reset your Apple Watch using your paired iPhone in the If you forgot your Apple Watch passcode.
Then continue with deleting and reinstalling the Watch application using the steps in How to delete apps on your iPhone, iPad, and iPod touch.
If you continue to have issues after these steps, the following steps are recommended.
- Temporarily disable the connection to any Bluetooth devices other than the Apple Watch.
- Try pairing and updating while the iPhone is connected to an alternate Wi-Fi network.
- Reset the network settings by going in to Settings > General > Reset. Please be sure you have your Wi-Fi password available, and steps to connect your Bluetooth devices again.
If these steps do not resolve the issue, please reach out to an available Apple Support channel through the Get Support website.
Take Care!