resuming portupgrade

if
   portupgrade -fav
fails at some point, and i fix the cause of failure,
how can i resume it?

e.g., i got

        + lang/librep (librep-0.16.2_4)
        + print/enscript-letter (enscript-letter-1.6.4)
        + print/freetype2 (freetype2-2.1.7_3)
        + graphics/gd (gd-2.0.25,1)
        + x11-fonts/fontconfig (fontconfig-2.2.3,1)
        ! x11/XFree86-4-libraries (XFree86-libraries-4.3.0_7)   (install error)
        * misc/hicolor-icon-theme (hicolor-icon-theme-0.5)
        * math/xplot (xplot-0.90.7.1)

due to 

    ===>  XFree86-libraries-4.4.0 conflicts with installed package(s): 
      xpm-3.4k

      They install files into the same place.
      Please remove them first with pkg_delete(1).

i de_install xpm, but how to resume the portupgrade -f?

randy