Kelly left an empty spot after she traveled
I think you can get away with it; however, phrasing it like this ("Kelly left an empty spot") implies that Kelly chose to create that spot (maybe not as the main goal, but she knowingly left an empty spot).
When you're talking about a dead person (who did not commit suicide, I guess), I would change the phrasing to:
There is an empty spot that Kelly used to fill.
It removes the implication that Kelly performed the action (leaving a spot by dying).
Kelly left an empty spot after she traveled.
I think you mean to say
Kelly left an empty spot when she traveled.
"After she traveled" means that she has stopped travelling when the empty spot is there.
That could be correct (e.g. she chose to stay abroad to live, therefore no longer traveling), but it could also be incorrect (she came back home after her travels).
To avoid confusion, I would say "when she traveled", to point out that the empty spot was only there during Kelly's travels.