I see he is still running low at +10.
So at shot time you have a couple of options.
1) If he is above 50 shoot the new full dose (4.5u), and monitor, based on recent experience he is likely to bounce after last nights low. If you look at the cycle in the morning of march 6th when you shot the depot reducing dose, if you look at the early part of the cycle you can see he stayed level and then bounced, that early part of the cycle would have likely been just about the same as if you had shot full dose. Since the shot you gave wouldn't have onset till about +2+3(for Sebastian that seems about the norm), by onset time he was already bouncing so the reduced shot that drained the depot will have contributed to the higher numbers at the end of the cycle, and may have also contributed to the length of the bounce. Shooting the full dose in the morning might lead to another busy cycle of monitoring if he surfs around in the greens.
2) shoot a reduced dose to reduce the depot and then shoot the 4.5u tonight. The early part of the cycle will not be influenced by the reduced shot, so you will still need to monitor until you see him rise or level out.
Things that may influence your decision.
If he is rising at AMPS I'd be more inclined to shoot the 4.5u, because you may well be seeing the start of the bounce so he's going to run high regardless of what you shoot so I like the idea of not disrupting the depot.
If he's still in the low 50's, and with the high IAA, I would err towards the depot reducing dose, last time you reduced by 50%, I might try and reduce by about a 1/3rd this time to 3u.
ETA your ability to monitor if you have to do stuff later in the morning then perhaps the depot reducing dose will be a better option and if he is high and bouncing at +11(pink) then you could move the shot time forward by one hour, getting you back on schedule with the DST.
I take it all is well, ie no ketones/he's feeling and acting well.
It's amazing what the threat of a dosecrease can do to a kitties BG

Congrats on the reduction.