For a person:
* Renew: This is the most common synonym for "re-sign" when referring to a person. It implies continuing a contract or agreement.
* Extend: This word implies making a contract or agreement longer.
* Retain: This word focuses on keeping someone, often in a position of employment.
For a document:
* Renew: This is the most common synonym for "re-sign" when referring to a document. It implies extending the validity or effect of the document.
* Reaffirm: This word emphasizes the act of confirming or making sure something is still valid.
* Reauthentificate: This word implies making sure a document is still authentic and valid.
Other options:
* Re-contract: This is a direct synonym for "re-sign", but it's less common.
* Resign: This word has a different meaning, which is to leave a job or position.
Ultimately, the best word to use will depend on the specific context of your sentence.