As yodon says, your risk analysis is critical.
Consider such things as:
1. Does changing the components potentially invalidate previous testing (e.g. EMC)? If so, re-testing is likely required. If not, document your analysis, and justify why the change doesn't impact previous test-results.
2. Does the change affect function, or device specifications? If so, this is likely a significant change.
3. Does the change affect your previous risk-assessments? Are these critical components necessary for safety/risk-mitigation?
The FDA has a pretty
comprehensive document on assessing the significance of a change.