If you forgot to extend the boost it’s your fault and not a mistake. You have to go without the mummy boost until you get it again. That’s the only way.
Just be more careful next Time.
I play about one year, the level of my hero is 105, I know a lot about the game. But nowhere is there any information about the fact that if you do not extend the military amplifiers in time they can not be activated! Why so, why do we learn about this only through such errors ?! After all, if we knew about this, this mistake would not be!??
You have to prolong war boosts on your own. You can’t reactivate them after they expired. It has always been that way