Looks like he may be bouncing from that 68 on the 23rd. Bounces can take 3 full days to resolve, sometimes more.
Since you're in the Relaxed forum, I'd suggest going back to the 1.25 dose and holding it steady for a good 7 days. Then, if the nadirs suggest an increase, only very slightly fatten the dose a hair closer to the 1.5, but not at it exactly.
Also, check your syringe markings. It is possible for syringes to have less than accurate placement of the lines. At the small doses cats use, this can wreak havoc with control. Some folks use calipers so they can measure very consistently.
Also, it looks like you entered directly onto the US mg/dL page, rather than on the mmol/L page. Its OK if you want to do that; the spreadsheet is set up to do the math for you if you enter on the mmol/L page, though as you get towards the bottom, you may have to copy the formulas down on the mg/dL page.