Trump appears to be utterly addicted to the rally. Where he can bask in the attention and approval he needs so badly. That is why he wastes valuable time and resource in states that he probably already has in the bag, he is the atom bomb of attention whores.
We've all seen outakes of his speeches, his "punch lines" that thrill/outrage the crowd. He doesn't give speeches, he gives improv. He meanders about, looking for something that gets that zing! from the audience. He does not lead his audience, he probes his audience for energy, and follows it. Improv politics.
Trump sincerely and mistakenly believes that rallies are an effective campaign tool, that preaching to the choir over and over will expand the size of the choir. It works great to fire up the people who are already fired up and in his corner, it has no useful purpose in bringing around the people who are looking for something presidential.
If he is to "turn around" his campaign, he will have to change his style, he will have to give up all that sweet ego juice for solid political practice. I don't think he can.