Douken grafito Matt 60 X 60

[Matt Bott]

there would also need to be access from the back enough to get a tool under the tile as you won't be able to do it where another tile is touching as the angle would be to great and crack / damage would occur

 

[One Day]

I would guess you can or will spend SO long trying to sort this out, you'll be better off accepting that you'll need to re-tile.
Possible consider going over the existing tiles with a thin porcelain?