How to handle tests for changed requirements, or requirement change process overall

How to handle test cases for a requirement? 

Example: I have created a test case linked to a requirement, the test case is executed then the requirement changes. There seems to be no way to trigger an event for this change? How do I know which tests to re-test? Can I find the associated tests for a changed requirement by filter/search somehow? If not, is there any other recommended way to handle requirement change? I can't seem to find a way to handle requirement versions, e.g. v1 of the test case is executed towards v2 of the requirement? What is best practice in SpiraTest for this?

There is no event currently triggered (planned enhancement) however you can run a Requirements Traceability Report and then see which of the test cases needed to be executed based on requirements that changed in a specific date range?

Regards

Sarah