You can't, because if the previous decision was C or D, your revision will immediately be sent for re-review after you click the submit button. Your best shot is (e.g. if you forgot tables etc) to upload a supplementary file which contains the missing pieces. Otherwise you'll just have to wait for the re-review reports.
If the previous editorial decision was B, then contact the editor, who may be able to upload a revised version.
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Remember: The manuscript must adhere to the appropriate article type format (e.g., word count, quantity of references, number of tables/figures, etc) throughout peer review, revisions, and at the time of acceptance. If the manuscript exceeds the stated formatting above, then the APF for the applicable article type based on format will be applied (e.g., if the manuscript was submitted as a Research Letter but then is lengthened to an Original Research Paper during revisions, then the applicable APF will be applied). See: JMIR Publications Fee Schedule.