As with all things to do with aviation there are several different options depending on when the cable breaks during the launch - including landing straight ahead, carrying out 'S' turns or completing a circuit to land (gliders 'glide' therefore have more options than powered aircraft in this situation).
Naturally, preventing a stall, by lowering the nose, and getting rid of the cable are important aspects of the process!
All practised during training and 'par for the course' (in my experience at least).