Of course you can do that. But know that attracting back a specific person is one of the hardest things to achieve with LoA, because you deal with so much emotions and doubts. You say you are not healthy for each other. Are you sure that it's really, really your honest desire to get him back? Or does your ego plays a part, because he dumped you? Do you fear to be alone? Do you think you will never find one like him again? Think about your motives and be honest to yourself. Attracting a new person is much easier and the good thing about a new person is that you have learned new things that you don't want in a relationship through your ex, so now you know more what you do want and could focus on that, if you so desire.
I don't want to talk you out of him, but my experience is that you are so hurt after a breakup that you would do everything to get that person back and in this stage you aren't in the position to attract him back. After a while, you see clearer and often you realize that it was good that the relationship ended.

Whatever your decision is, you have to work on yourself. You attracted an emotional unhealthy relationship, and if you don't change your vibrational patterns on this topic the same thing will happen again and again - with this guy or a new one.

And you don't attract him back by "trying to make things better" that sounds to me like physical action. Of course you push him away, if you don't adjust your vibration before you take action.