This is what I did and still do. We meet most weeks for an hour or so, walk and talk or just take a coffee together when time or weather demands. Our conversation moves between English and German, and as my German has improved so has the depth and topics of conversation. We also send each other messages in our "foreign" language and the other corrects mistakes. Really made a difference for me and also enlarged my contact base as I met her other friends, so now I have lots more people to practice with when I meet them on the street or in shops.