Battery health backup

Sorry, but the battery capacity can't be set back, since the battery degrades over time.

This is a chemical process that can't be reversed.

The only way would be getting the battery replaced by Apple or an Authorised Apple Service Provider next to your place.

iPhone Battery Replacement - Official Apple Support

Apple - Find Locations

ghanshyam19 wrote:

I think there shoul be any app or something to backup battery health

What you're suggesting is more like rolling back a vehicle odometer. There's nothing that can restore the capacity of a lithium-ion battery.

Yes. Have a new OEM Apple battery installed by Apple or an Apple Authorized Service Provider.