I don't know if she had this revelation. The Church did not teach about this if she had known, but she didn't need to know this. She walked in faith until the end as an example for us.
She did not have the Beatific Vision like what our Lord had in his humanity. Only He, as a human being, had the Beatific Vision and knowledge from God. For Our Lady, she did not have this, so I don't know, but she probably simply walked in faith and trust in the Lord. She had the sole desire to meet Him, so we cannot say she had a revelation before she died.