Paragraph 13 decision 1/CP.21 is clear that countries do not need to submit NDC with the instrument of ratification if they have already submitted the INDC. In this case, the INDC will be considered as the NDC. However, countries that have submitted INDC can submit a revised version with the instrument of ratification, if they wish to revise the INDC.
It is not mandatory for countries to revise the INDC and submit as NDC. It the country considers that its INDC is final, then there is no need for submitting a revised NDC together with the instrument of ratification.