What kind of evidence would be needed in order to change any part of cell theory?

In order to prove that the cell theory is not right, one must have evidence to prove that cells are not the building blocks of life.

One might want to prove that the theory of spontaneous generation was indeed right in order to discard the cell theory. The theory of spontaneous generation, brought up in the past, suggested that all living things arise from non-living things which was proven to be wrong.