If you have synced your wallet using an API/auto-sync then you have the option to resync the wallet from the beginning. This will not affect any of your previously synced transactions but it will sync any transactions that have been permanently deleted or, in very rare cases, sync transactions that the API skipped.

This button can be found on the Troubleshoot page for your wallet.
Just click on the specific wallet and then click on the 'Having trouble?' banner. This will open the troubleshoot page and you will see the option to 'Resync wallet from beginning' on the left:

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