Is using a lease addendum to extend a lease ok after expired term for a M2M Tenant?

[Tommy Dians]

Hi all, I usually just make a lease addendum when extending a lease, but due to the economic situation of a tenant the original lease term expired about 2 years ago and we have been month to month since then.  Even though the original lease term expired there is a section stating that the lease will continue month to month as long as the tenant pays and I accept, which has been the case.  Now the tenant is ready to extend the lease long term, so is it still fine to just make a simple addendum to the original lease instead of drafting an entire new one?  This is a commercial lease by the way. Thanks in advance!