Deciding on resits post-application?

Technically speaking, if you decide to enter for resit exams after you've submitted your UCAS form, should you contact the unis to inform them?

You must write to us immediately if your exam subjects, modules or units, awarding or examining board, centre number or any other details change. You must also tell the universities or colleges where you have offers or those that are still considering your application.

Of course, both to comply with UCAS rules about notifying changes to your application and to ensure the universities can obtain your results in time for results day.

http://www.ucas.com/students/offers/makingchanges