Hello,
The easiest way to have your target use the most recent txt file is to manually "Deploy All" from your project each time it is updated, and include the txt file under your Real-Time Target in the Project Explorer Window. That way, everytime you "Deploy All", it will deploy the VI & txt file to your target.
There is no way to programmatically deploy a txt file that I know of. You can possibly programmatically deploy the txt file, and
this forum post mentions how you can use a VI on your host computer to ftp the files. However, you cannot use these commands from your VI on your Real-Time target, so this method might be a little more complicated and not worth your time if it is only for development purposes.
I hope this helps!
Kameralina