The point of directives is that they concern areas of law where the EU does not legislate directly. They create a requirement that member states must achieve through their own legislation. In the EU's own words
A "directive" is a legislative act that sets out a goal that all EU countries must achieve.
Were a directive to be repealed, it would remove a constraint on national law. That would not automatically lead to a repeal of national law. Of course, national law itself could have a provision effecting the automatic repeal, but that might be problematic because most repeals seem actually to be modifications or recodifications, where national legislatures might be better off amending their transposing legislation rather than replacing it.