As Ali mentioned, there are several choices available to you. Several companies make small centrifugal filtration units that work well. You can also try precipitating protein from the conditioned media using trichloroacetic acid. Both approaches work well, but are not without drawbacks.
In the attachment you can find a paper that includes a method for enrichment and analysis of secreted proteins from the filamentous fungus Podospora anserina. It can be easily adapted for use with other species of fil. fungi.
Success for your work!
Article PaCATB, a secreted catalase protecting Podospora anserina ag...