I know it would normally be sacrilege to "destroy" art, but have you considered scrunching this up to a ball, flattening it back out, then scrunching it back up again, and flatting it out again, then scanning it to introduce the texture, before the piece could be framed under glass?
I know that's a bit hard for a digital painting, but I am tempted (with your permission!) to print this out and attempt to do so myself! :D