Can I renew a SWMS record after its 'valid to' date has passed, or it has been archived?

No, not directly. SWMS can only be archived after their valid date has passed so that a historical record of a SWMS for a specific time period is preserved. However, an existing or archived SMWS record can be cloned, where a new 'valid to' date can be specified after any necessary updates have been applied. Also note that Archived records are hidden in the list view by default: