I've got three months to revise my manuscript I submitted to a journal a few months ago. I received two highly detailed reviews, from which it seems that the manuscript does not show the desired big picture of my work. Both reviewers pointed out similar deficiencies, and I must say, both of them are right.
According to the questions, remarks and advices, I rethought the entire paper and started to rewrite it (being attentive to the reviews), however, I am not sure if it is acceptable to completely modify the whole manuscript. Obviously, the background, the results, the theories and everything concerning the main content would remain the same with slight modifications, but I think the restructuring of the content and even a completely rewritten introduction would be necessary.
So my question is:
How much modification is acceptable after a moderate/major revision and after the decision of rejected with the chance of resubmission?