ModiBatudu

You want to check when a certain file was last modified. If the file age is too old,you want to check for an internet connection. If the internet connection is present, you want to run a batch file. If the internet connection is not present, remind user to connect. If the files are recent/upto-date,do nothing.

Download and unzip the tool to a folder of your choice.
ModiBatudu.exe is the executable you are looking for. It runs based on the parameters set in ModiBatudu_Config.xml in the same folder.
Have a batch file ready, the one that you want to be run, from time to time. At the end of the batch file, ensure it writes to some text file about the last date and time of update.
Set the parameters in ModiBatudu_Config.xml, mainly the batch file you decided above and the frequency you want it to check. The xml file has in-line comments to guide you.
Set ModiBatudu.exe to run on a scheduled task in Windows at whichever frequency you want.