Short answer, no.
Long answer(sort of) it has been indicated when I asked this earlier that if you had the knowledge and invested a lot of time in modifying your save, delete all the blocks/items that have changed beyond the possibility of replacing them and solving all the conflicts etc, it might be possible to save some parts of it. But I think it would be rather pointless in the end since you would end up with a rather disjointed world after spending more time than it would take to just build it all again.