I would say do not go making any changes to your ratios while you are still sick since things will change.
I find that when I am ill I do need to increase my doses a little bit (also just had a cold) so it is not unexpected.
Do you know what the effect of 1unit of insulin is on your BG? Also have you been testing for ketones? It could well be that you have raised ketone levels and this can effectively seem to soak up some of the insulin you are giving as a correction.
One thing that may well be happening is your Levemir may not be enough. Have you tried doing a carb free dinner so that you are not rolling a bolus into the mix to see what happens over night? Also during the day do your levels creep up?
First try and work out what a 1 unit correction dose does to you so you can figure if you are in fact dosing correctly, next have a look at some carb free meals to see if your sugars still rise over time. If that is the case then you may need to bump your levemir dose a little.