How to push existing job/label logs data to another loki instance?

I have collected logs using loki and now I want to push only specific labels or job logs data to another loki instance running on different machine.
I have went through HTTP API page Loki HTTP API | Grafana Loki documentation

But using

POST /loki/api/v1/push

It will push new label and associated values data to loki instance which I don’t need.

Anyway I can push existing label / job logs ? Any help is much appreciated.