trouble with mosaic attempt

[dcfkaf]

I tried my hand at mosaicking broken tile on a dresser top. I read the directions wrong and left the grout on everything overnight. I'm having a terrible time getting the grout off some of the tiles...any easy ways of removing it? Also, the grout seems to have shrunk and now it doesn't sit level with the tiles. If I let it sit longer, to really dry thoroughly, can I add grout on top of the existing grout, to bring it level with the tiles? I have not sealed anything yet. (In fact, I'm still peeling grout off the tops of the tiles!)

Thanks so much for any suggestions!