I find participatory exercises can help, such as, making that student one of the helpers in a demonstration and using their name to make it personal. Pulling them into focus resets their thinking patterns and "wakes them up".
Physical activities where the students are forced to move out of their comfort zone and interact with each other (where possible) seem to break the barrier between their preoccupation and the topic, as other students pull them into the content.
Varying the method of delivery can also help, if every lecture follows the same schedule/format, then I think students can easily fall into set behaviour patterns.
