Having never missed one and stab myself religiously at 8am on the dot daily, I've never given it much thought; but, I was told it has a half life of around 18hrs, so 36hrs would have passed before you were completely drained of it.
Personally I would inject the 1.2 as soon as I could (noting the time) and then adjust my timings each day by an hour from that time until I was back to 8am again.
I can't remember if there is a help line number in the pack but I'm sure Google will find it for you if it really worries you.
If you do get a definitive answer, please share it with us so we all know where we stand with a missed or very late dose.