The short answer is that the HbA1c will show what your readings have been like over the last three months, but will give more emphasis to the last three weeks. Trying to have really tight control for three weeks will make some difference, but won't completely hide the previous weeks.
Without wanting to judge you (as we've all done similar things!), the longer answer is that I think you should really talk to your healthcare team about why you feel you don't want to take your novorapid. If you don't want to talk to your team, is there someone else you could talk to? It is important that you do take your novorapid as your levemir alone won't do it. I bet you know that, but if something is making you feel like you don't want to take it then I think that is something to look at, rather than hiding it.
You can always talk to people here by posting or by PM. Feel free to PM me if you want to, although you will have to post a couple more times before you're able to PM.