Lost drawings, comments on Dropbox file

I was drawing and making notes for 2 days on a Dropbox document as I have done in the past on my ipad utilizing the Dropbox auto save function, again as I have done numerous times. At the end of the day I stupidly turned off my ipad.  When I turned the ipad back on, all drawings, notes, edits were gone, only the original 362 page document. Is there a way to retrieve the drawings, etc? Thanks in advance for any input.