Autofill on a modified paragraph

[Giannandrea Castaldi]

Hi all,
when I'm writing a text in a text mode the autofill insert soft newlines 
so that the lines aren't too long.
But if I change a paragraph the autofill doesn't reformat the whole 
paragraph, I must reinsert spaces in the right positions so that it 
reinsert soft newlines.
There is a way to apply refill on the whole paragrath/buffer?

Thanks a lot.

Giannandrea