Vuejs: Lifecycle hooks of child routerview components using keep alive

I'll explain my issue in a more generalized way for the purpose of clear understanding and here is the jsFiddle

I have two main routes which show two different components in the router-view

Route-2 contains a another router-view inside it which displays two sub routes that are:

When Route-2 is clicked it opens the component of Route-2 with sub-route-a pre-opened in its router-view

Both the main router-view and the router-view inside Route-2 are wrapped inside keep-alive tag so that they are cached

Caching and everything works fine as expected.

I added all the lifecycle hooks and using console.log to see which hook is called

For the first time for all components as expected the beforeCreate() , created(), beforeMount(), mounted() hooks are called.
since the router-view is under keep-alive element the activated() hook is also called
whenever I move to and fro between Route-1 and Route-2 the activated() and deactivated() hooks are called when entered and left respectively for each component

Here comes my problem

Since when Route-2 is clicked it opens the component of Route-2 with sub-route-a pre-opened in its router-view, all lifecycle hooks of sub-route-a componenents are called only once
when I go back to Route-1 deactivated() of Route-2 is called but no hook of sub-route-a is called.
only when I toggle between sub-route-a and sub-route-b the activated() and deactivated() hooks of these components are called
on subsequent entering of Route-2 activated() hook of Route-2 is called but no hook of sub-route-a is called
I want to cache sub-route-a but make changes to it on every enter. So where do I put the code since no lifecycle hook is being called excrpt for the first time.
**I don't want to use ** beforeEnter()