There are many situations when testing a BCDR plan is appropriate or mandated.

Regulatory changes by themselves would not trigger a need for new testing of a BCDR plan. Any changes necessary for regulatory compliance would be accomplished through configuration changes or software updates, which in turn would then trigger the necessary new testing. Annual testing is crucial to any BCDR plan. Also, any time major configuration changes or software updates are done, the plan should be evaluated and tested to ensure it is still valid and complete.