You can't change residency information through ReFile. You should contact the CRA on how to proceed, as changing your residency status and how long you were a resident might significantly change your return.
If you are in Canada or the United States, you can call the CRA at 1-800-959-8281. If you are elsewhere, you can call 613-940-8495. This page has more ways to contact the CRA: Contact the Canada Revenue Agency
