Say I 3D render out an image sequence, do some video work then re-render over the original files, in After Effects I can right click that image sequence in the file list and hit reload and it will reload those files from disk and clear the cache so you see the updated sequence in your composition.
Premier doesn't have this feature, sometimes it just updates anyway but often it doesn't and the only real solution is closing the app and reopening.
I use a different rendering process, and at this time, there's no need for this (the GPU can do all the work real time).
Everything I've dealt with so far didn't require pre-rendering yet. I may end up doing this in the future for insanely complicated scenarios. Otherwise, I do a lot of optimization behind the scenes for loading the video frames (I've made my own PRORES-lookalike format), while applying all effects on the GPU.
If I will end up implementing this, I will also allow for a Refresh footage button :P