Repeals
Yes, you can Repeal, provided you use the Repeal function. If you make your own Proposal in some other category and calling it a 'Repeal', it's going to be deleted. Remember, Repeals can only repeal the existing resolution. You can provide reasons for repeal, but not any new provisions or laws.
Furthermore, simply stating "National Sovereignty" (i.e.: "this law prevents my nation from doing Y, X, and Z", or "this legislation will destroy the moral fabric of our society") is not sufficient grounds for a repeal. Since such a stance could be used on every single Resolution, it is little more than saying "I don't like it." Religious, cultural and ethnic sovereignty also falls under the umbrella of 'NatSov'.
Also, Repealing on the grounds of an old Resolution violating the current rules is not sufficient. On a more practical side, Repealing because a Resolution violates the rules is itself a MetaGaming violation: the laws do not "exist" from an In Character standpoint. NOTE: A Repeal must have an active "Repeals" clause.