Create surface on dwg imported

Hi, i have imported a DWG 2004 file on Sketchup, make with Bricscad.
Now, to make a rendering with photomatch i need to create surface where bricscad was simple area defined by line/polyline.
See here:

I can close linee imported to move sketchup to auto-create surface, but it is so long and boring.
I can make this with other way? a plugin, another technique?

You should upload the picture here directly.
There are many plugins that can create faces for closed and coplanar, e.g. TIGs Add Faces or Eneroths Face Creator.

Depending on the quality of the imported quality, you can have a look at Thomthoms Architect tools too.