déjà vu does not have to be a visually perceived. Maybe kinesthetic methods would be more conducive to inducing such a sense. Doesn't déjà vu come with some vertigo? Maybe it's is wrong to say déjà vu is an experience, rather it's a mode, a way of interpreting what's happening. Maybe trying to induce such a mode, we'll discover ways to condition events with some other effect that won't fit the label "déjà vu" but which we'll find equally interesting. Just "zeroth order" effects of repetition could be an easy starting place: repeatedly showing representations of a situation.