I'vebeen on levemir for about 7 years, it is a bit of trial and error to start with, but I'm on Novorapid as well, wich is quite 'spikey' in its delivery. When doin my conversion, I concentrated in getting nightime levels right 1st, as there are alot of variables throuhout the day, try eating same food for main evening meal @ same time, take same apidria as usual for the carbs, I'd advise underestemating levemir dose, so you have a bit of room to play with in reguards hypoing during the night, and test every 2 hrs to get an idea on how its working, levemir is quite 'flat' in its dispersal, so I'd suggest making sure you take a test @ about 4am, that'll give you a rough idead how its working when your fast acting shuld be spent....
Thats my suggestion..
Good luck
Bob