It seems that new emacs 23.1 allows viewing of pdf,
cfr.
http://www.gnu.org/software/emacs/NEWS.23.1



"""
** DocView mode allows viewing of PDF, PostScript and DVI documents.

One can also search for a regular expression in the document.  For
details, see the commentary in doc-view.el.

PDF and DVI files are now opened in Doc View mode by default.

In Postcript mode, C-c C-c launches Doc View minor mode for viewing


the postscript file.
"""

I believe that each page of pdf is converted in png, so maybe there is no refresh .

--
luigi