To achieve expected functionality we can use WeblogsUtility.exe available at location \TIBCO Nimbus\Client\Utilities\.
You can run the WeblogsUtility as a windows scheduled task, where you run the Weblogsutility, save the settings to a file (WSE).
Steps to be performed,
1) Run WeblogsUtility present at \TIBCO Nimbus\Client\Utilities\
a) Select the PR
b) Select the output/Export file
c) Select all the export options you want - date range (you can select 1 Month) - what you want to report on
d) Save settings to a WSE file
2) Open a command line to test if it works - format is <Location of Web Log Utility>.exe\ "<Location of Settings File>.wse"
example
"C:\TIBCO Nimbus 10.2.0\Client\Utilities\WebLogsUtility.exe" "C:\TIBCO Nimbus 10.2.0\Client\Utilities\TestWSESettings\TestWSE.wse"
If this works then you can create this as a windows scheduled task.
More details related to WebLogsUtility can be found in the Admin Guide if you search for WebLogsUtility.