Since you're using Novolin, you don't want to shoot anything under 200 because of the harsh nature of that insulin
Generally, if you're getting Preshots that are too low to shoot, it's a good indication that the dose is too high, so I'd probably skip tonight and if he's high enough in the morning, go with 2U and see how he does
Could you please add some information to your signature like:
Your name/cats name, age, sex, date of diagnosis, type of insulin, type of meter, type of food, any other health problems? and a general location
Having to go back and read the entire thread to remind ourselves of what's going on and this basic information takes a lot of time....and in a crisis, it's time we might not have.