You keep using the term "rewrite" which automatically means that the original cello part and its writer has to be considered (in my opinion).
A different (and maybe better situation) would be completely scrapping the original and starting fresh with a new cello part!
I once had a situation where I had to seriously re-write the lyrics to several songs and some years later the lyricist decided to go find someone else to write the music (he liked what we had already done, but I wasn't available to him anymore to continue to pursue the project which was a musical). I had to remind him to use his ORIGINAL lyrics (which were terrible) when he found someone to write the music and I printed out copies of his original lyrics which I gave him.