International Entertainment Law - Question about modifications/addendum to current contract for performance in Peru

You can suggest a choice of law and see if you can get the contract construed under the laws of the state where you reside, but that won't save you in the event of an issue. In order to effectively assess your needs a lawyer would require all of the information (much like the information requested by the others who tried to respond to your post): who are the parties, what are the obligations, what are the protections in place already. And no matter what jurisdiction is chosen for the construction of the contract, you should be aware that realistically enforcing a contract with a party in a foreign country can be tricky and expensive. It is not recommended that you find a qualified and experienced lawyer to help you handle the drafting and negotiation of all of the relevant legal issues. If you are traveling with a group or on a tour there might be some additional information you can get your hands on. Otherwise look to the person who booked the show to determine who the parties are and start there.

What "legal protection" are you talking about? That you'll actually get paid for your performance? That if you fall off the stage your medical bills will be covered? That if your equipment causes damage [to a person or a thing] that your insurance company will consider it a covered claim? etc. etc. etc. List whatever you're concerned about and bring the list with you when you chat with a US-based entertainment attorney. Absent specifics, no one can provide you any meaningful advice. Good luck.

Have you been presented with a personal appearance contract from someone, or are you supposed to supply your own? Do you have a promoter? A booking agent? A touring corporation that furnishes your services and provides a liability shield? Musicians that tour nationally and internationally usually have some or all of these things which make this smoother. It's not clear what you've got, although your query seems to indicate that you've got a contract that's "current and satisfactory." Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.