You seem familiar with the if ... else structure, which makes me wonder why you don't do something like this
if exist "!file_path!*.spl" (
echo Searching for spl files...
dir !file_path!*.spl /b > SPLfiles.txt
) else (
echo.
echo No spl files found
echo.
echo Press any key to finish . . .
echo.
pause>nul
exit
)
REM Note: you will only get to here if at least 1 spl file was found
I have chose to redirect the pause output message "Press any key to continue . . ." to nul and substitute another, because I sometimes feel the word "continue" is inappropriate when you are in fact not continuing but finishing.