Repeat same table or figure in different chapters or use cross references?
First off, a dissertation is a very unusual document, which tends to have a lot of authorial flexibility in its presentation.  As such, there's often a lot of possible latitude for choices that would not be permitted by a more conventional publication in a journal or conference.

That said, here are the guidelines that I personally would use for considering the options:


If the table is primarily for purpose of ease of reference (e.g., table of notations), then using it more than once is fine.  Typically, one would want to reference the first copy. In some cases, however, I might not even think of it as duplication so much as convergent evolution and not needing a reference: e.g., "notation used in this chapter" might just end up with lots of overlap for some chapters.
If the table is a "significant" object presenting technical / results content, on the other hand, then reproducing it feels less appropriate, because it is taking the material out of its context of presentation. The exception I see here is if it is used as a fragment of a larger comparison, like when an image is presented again in order to allow direct contrast between it and other images.