You would need to get the ‘statutory Declaration? signed by a qualified official who has the authority to administer an oath or solemn declaration, for example; a commissioner for oaths, notary public or lawyer. As you are in the US, a qualified official includes a Canadian or British diplomatic or consular representative, or a qualified local official.
For Canadians residing in the US (whether temporarily or permanently), the only ways to renew or apply for a new passport are to either mail the application to Canada, or to travel to Canada in order to apply in person. However, if you apply by mail, please be advised it may take up to 6 weeks to get a new passport, provided everything is right with the application.