first see if your ftp client produces a result or errorlevel upon its completion.. if so then test for it using a "if errorlevel == " to steer your batch.
you might also be able to pipe the result code to a file upon the sessions completion. Look for info on loading result codes and piping output to variables and other devices.
Piping is done via "|" dec 124, shift of the "\" key on some keyboards.