Really important - Lantus doses are not adjusted on the preshot value; they are adjusted based upon the lowest value between shots, the nadir. The stickies posted in Lantus explain how to use Lantus to its best effect and I encourage you to read them thoroughly, even print them out.
Also, you should give the same dose, at 12 hour intervals, without adjusting on the fly. Based only on what you've described, either a fat 1.0 or a skinny 1.5 might be the right dose for your cat. You'll be able to determine that after doing a curve over 12 hours - testing every 2 hours, from before the morning shot, to before the evening shot.
You estimate 0.25 increments between the half unit markings, using the same side of the line on each end (both top edges or both bottom) and carefully draw the syringe to your best estimate. Some of us will use 'fat' doses where the syringe edge is just a bit above the marker line or 'skinny' doses where the syringe edge is just below the marker line (where above means away from the needle and below means towards the needle)
