Lyric discussion by ConfinedInfinity 

Cover art for Miserere lyrics by Gloria Record, The

Not only does it mean "to pity," but Miserere is also one of the Psalms, so this song definitely has some Jesus and/or religious reference. It's also more specifically a penitential Psalm, so you can get the idea of rebirth in this song, perhaps resulting from a regret of some sort. And the lowercased miserere is a prayer for mercy, or a complaint.

That's just what I've found after some research. It's pretty interesting sutff.