It's clear that "No matter where you go, there you are" has some significance we just don't know yet. My aim with this is to ask if perhaps part of the mystery lies in some of the instances in which "there you are" is used has added significance in a return to some of these instances. Grave Peril being a prime candidate for Harry to return to in some capacity. I'd argue Changes as being another instance, not to mention Harry's take down of HWWB when he was just 16 years old.
So, Id Harry tells Harry "No matter where you go, there you are."
Uriel tells Harry the same thing "No matter where you go, there you are." This was something Uriel considered useful for Harry to know, though Harry was totally clueless as to what it meant.
Reviewing some of the instances' I'd say Mrs. Spunklecrief had a hidden conversation with another Harry that was present and overlayed on top of Harry in Changes.
Harry returns to some of the events in Grave Peril. He returns in some capacity to Changes.
Some futuristic Harry assisted a younger self in the flashback to Harry vs. HWWB. Alternatively, a Archangel whispered words into the ears of a young Harry to help him defeat HWWB.