Who holds the group together? Are there student leaders or full time workers? How do you reach out to students, other than inviting them to Bibelstammtisch or parties? How do or did you get students involved and ready to reach out to fellow students? That seems one of the issues here - everyone loves hanging out with the American STINTers (Short Term International, they come for two years after college just to live life here and start conversations about Jesus on campus), but nobody is willing to invite friends or do evangelism themselves. It would be great to exchange experiences!
We loved doing campus ministry in Germany. We were part of great group called Connexxion, www.goconnexxion.com that has a focus on Discipleship and Evangelism. The ministry started in Jena, about 2.5 hours south of Berlin, and has expanded to Braunschweig, Hamburg and Sevilla, Spain. They have semester retreats and are always open for new friends, especially ones who work for groups like Crusade. I myself was a Crusader during my time in College at Georgia Tech in the early 1990's.
Check out Connexxion's website and let me know what you think and if you have any questions. I can get you connected to any of the leaders and/or the founder of the group very easily.
My wife and I served as Campus Ministers in Germany for three years from 2005-2008. We have many ministry contacts in the country and would to connect you to some disciplship oriented campus ministries if you have interest. Tschüß .