Hi Omar,
I agree with Dreamer. Falling asleep isn't bad in itself, it demonstrates that you are actually relaxed while listening (this is essential!) and you are entraining to the alpha, theta and delta brainwave frequencies (which is the goal of BrainEv). Remember that alpha is a very, very relaxed, suggestive state to be in, theta happens when we are semi-conscious i.e. falling asleep or you have already fallen asleep, and delta is the zone of the unconscious i.e. deep sleep. So it is not a surprise that most of us fall asleep at some point during the BrainEv session.
For your brain it is a new experience to experience lower frequencies such as theta and delta AND REMAIN AWAKE. I consider it normal that we have a tendency to fall asleep during sessions because this is what our brain is programmed to do when the brain naturally produces theta and delta = we sleep. Consider it normal if you sleep or have a sensation of 'loosing time' during the first week or two of each level. BrainEv is pushing your mental boundaries each time and you have to be fit enough and learn to remain awake during low frequencies.
As Dreamer suggests, change your position to 'inform' your body and mind that this is NOT SLEEP TIME yet. Sit up straight, or better sit cross-legged on the floor like a yogi. Right now I am working with an alpha program (not BrainEv) which even suggests standing up, if the urge to sleep becomes too great!!!! I have not tried this yet, partly because I am afraid of falling over, as I find the self-induced alpha very, very, very hypnotic. Another idea is to change the time of day you do your session. Sometimes all it takes is a little change to inform your mind that this is BrainEv time and not sleep time.
Regarding your question as to whether to repeat the levels. The BrainEv instructions is to stay four weeks on each level and then move up. I am now on my second round of BrainEv, and I now regret my rush to move ahead and get onto the 'really powerful' levels of the program. If your intuition tells you to stay on level one for longer, go ahead, do it. It cannot harm you, and there may be benefits later when higher levels can cause problems for some of us. Perhaps it is best to be fit in each level so that the higher levels are more beneficial rather than being too challenging.
My suggestion is to do BrainEv every day (one rest day after 6 sessions) and ENJOY the journey. It is a journey, not a race. There is no prize for finishing in exactly 6 months. The real prize is being able to recognise what if feels like to be in alpha, theta and delta and later to be able to move into these brainstates at will. Why hurry?
I wish you well on your amazing, personal journey into brainwave frequencies and how they affect you personally. All the best, Pure Bliss