How do I recalibrate the battery of my phone?
Recalibrating your battery won't actually make it last longer. What it might do is ensure that the battery level display is more accurate, so that when it says it's at zero, it's actually at zero.

Personally, I used an app like Battery Calibration (requires root) and it seems to help. To be fair though, I haven't actually tested the actual levels myself, so it's a qualitative judgement.

If you're having battery life issues it's more likely that you apps running (background or otherwise) that are draining your battery. Either go to Settings > Battery and check out which apps are draining your battery the most - typically it will be your screen, then cell/wifi radios.

Sadly, the only true "reset" is to go out and buy yourself a new battery. Sorry!