You will need to configure a second InfluxDB connection in the Kapacitor config (see the InfluxDB sub-section and the example config on GitHub).
Each InfluxDB connection has a name in the configuration, for example, influx2:
# Multiple InfluxDB configurations can be defined.
# Exactly one must be marked as the default.
# Each one will be given a name and can be referenced in batch queries and InfluxDBOut nodes.
[[influxdb]]
# Connect to an InfluxDB cluster
# Kapacitor can subscribe, query and write to this cluster.
# Using InfluxDB is not required and can be disabled.
enabled = true
default = true
name = "influx2"
urls = ["http://localhost:8086"]
...
You can specify which InfluxDB instance to send data to using the .cluster() property method of the InfluxDBOut node, which takes the name of your database as defined in the configuration as a string argument. For example, if I wanted to send data to the database influx2:
stream
|from()
.measurement('my_old_measurement')
|influxDBOut()
.measurement('my_new_measurement')
.cluster('influx2')
.database('db_name')
