When J is fighting Boris he looks at his watch before charging at Boris, letting himself get hit. it appears that he was trying to remember where Boris shot (Left, Right, Left) before he grabs Boris and throws himself and Boris off the top of the Launch Tower allowing him to redo it by doing a Time Jump.
The second time however Boris shoots in a different order, it's Right, Left, Left. not to mention he also got off a forth shot and it doesn't seem as if Boris did the Time Jump aswell
So what was the point to this Time Jump if Boris attacked different?