If you are interested in preserving your permanent residence for naturalization purposes, you can file Form N-470. I would recommend getting your U.S. citizenship as soon as possible to avoid the worry of losing your green card. Feel free to contact me for more information.
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You need to apply for a reentry permit that is valid for two years. It serves as the best evidence that you did not intend to abandon your status. You will need to be in the US when it is filed and to later do the biometrics. Two years later you will need to return to renew. You can also look at an N-470, but it sounds like you might not qualify based on the bit of information that we have here.
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