what should the bleach creator do to revive bleach?
1. We don't need another war. One just ended...
2. Grimmjow is dead. Kubo confirmed it in his interview that someone posted here a few weeks ago. Kubo apologized that he didn't show Grimmjow's death on screen.
3. Aizen is alive. He was sentenced to some-20000 years in prison. Pay attention
Anyways, all Kubo needs to do is progress the story. There are dozens of things that still need to be unveiled:
-Isshin's background, possibly including his relation to Ryuken
-Ichigo's newfound Shinigami/Fullbring powers
-Status of the other Vizards
-The Soul King
-Unohana in battle...
In fact, Kubo said that Unohana will be in battle in the next arc. Her zanpaktou will be revealed and her large hair braids will be undone while she fights.
If you want the interview and translation then look around these forums for the thread.