I've had dancers ask questions like, "Where are you staying?" and "Are you staying alone?" when I've just told them I'm from out of town.
Last night for example, during a lap dance with a dancer from out of town, he asked, "Do you live alone?"
Questions like that often indicate a good direction for the conversation to lead to private arrangements.
In answer to the OP's question, when you and a dancer are discussing a lap dance, or during/after a lap dance, you can always say something like, "If you ever want to do more than a lap dance, let me know." Just a simple sentence that can either end there or lead to a more promising discussion.