Or set a calendar entry that repeats once a month and use ProfileMatic's calendar rule.
#!/bin/sh # reset the data counter datetime=$(date +"%d.%m.%Y.%s") gconftool -s --type string /cellui/settings/datacounter/transfer/gprs_home_tx_bytes "0" gconftool -s --type string /cellui/settings/datacounter/transfer/gprs_home_rx_bytes "0" gconftool -s --type string /cellui/settings/datacounter/general/gprs_home_last_reset $datetime