I really like what Barry Danielian uses.
Easy to implement and very focused approach.
How to Play High Notes On the Trumpet! - YouTube
I also like playing eighth notes starting on C below the staff to G on the staff and then playing it one octave higher, trying to have the exact same relaxed feeling as the octave lower run.
Rest after each run as long as played. Then play each run 1/2 step higher , playing the low run first then the octave higher & again concentrating on the relaxed feeling of the lower run when you play the higher run. Just as Barry does, when you get to the top of your range your are done. Come back the next day and start again and work on building it higher by 1/2 steps.
Endurance, play a lot and don't damage your embouchure in the process, so limited pressure. Also, A PETE (Personal Embouchure Training Exerciser)by Warburton really helps when you can't get to your horn.