This is *[Isekai Shoukan wa Nidome Desu][1]* (One translation I've found is "It’s my Second Time Being Summoned to the Other World")

[![Front cover of the fifth volume of *Isekai Shoukan wa Nidome Desu*][2]][2]

> When his entire class gets summoned to Destinia Kingdom, Suzaki Setsu is oddly not taken by surprise
Unbeknownst to everyone else, Setsu had already saved the exact same kingdom in a previous life!
As a returned ex-hero, he sets off to prevent yet another impending war but not as a newbie anymore.

Found by searching for *isekai manga summoned back*, which brought me to [this Reddit thread][3].

It's apparently based off of a web-novel.


  [1]: https://myanimelist.net/manga/101226/Isekai_Shoukan_wa_Nidome_desu
  [2]: https://i.sstatic.net/GU7fum.jpg
  [3]: https://www.reddit.com/r/manga/comments/9wjnqi/summoned_twice_isekai_manga/
  [4]: https://ncode.syosetu.com/n6649co/