Force all states to explicitly follow their state law, as approved by the legislature, removing any and all votes that did not pass muster based on the laws as written and approved. Otherwise, if they don’t want to do that give them a choice of re-voting.
No mechanism in the Constitution for a revote. What would happen, if I read it correctly is that the state legislature (Repubs in all states in question here) would declare the vote invalid, due to it not following the law, then appointing the electors as per the Constitution.
Someone correct me, if I am wrong, please.