Wow!
Given he still went low with a furshot yesterday I'd be careful. Technically your new dose is 2.25U but I don't think I'd give that much.
If you haven't already, test again. If he's flat, I'd give a very very small dose (like a drop to 0.1U). If falling, I'd lean towards skipping, but test for ketones given the history of DKA. If he's coming back up, your call. I'd only give full dose if you can monitor all day.