I wrote a small perl script today that takes the timesheet .csv file that LiquidPlanner can export, and creates a new .csv file from it for an invoice for those tasks.

Like a lot of code people write and give away, I wrote it specifically for my needs and it's unlikely to exactly meet your needs without some changes & setup.

Here's the code, in the public domain in case it's useful. I'd love to see any improvements you make. 

If you're not sure what a perl script is or how to adapt it to your needs, I'm afraid I can't give free support but if you have a programmer or web guru friend they can most likely help, this isn't very complex as perl scripts go.

My specific needs were:

• I'm exporting data for one invoice at a time from Liquid Planner
• My client name in Liquid Planner matches the client name in Zoho Books
• Liquid Planner has my billing rate, and I've hard coded a product as 'Standard Hourly Rate' for now. I might need to make this more elaborate in future.
• I enter a lot of small tasks into liquid planner so I prefer to group my tasks by date, showing all the day's tasks in the description then the day's total hours spent.

Let me know if this helps anyone :)