Here are the intructions to shift the time of you GPX file, especially useful if you have just bought an Aldi GPS watch:
Download and install GPS Babel.
In the folder where you store your gpx files create a new text document and rename it
GPX minus 1hr.bat
making sure you change the whole file name including the file extension
Edit the file by opening it in notepad
Paste this code in and save:
SET file=%1.old IF NOT EXIST %file% copy %1 %1.old "C:\Program Files (x86)\GPSBabel\gpsbabel.exe" -t -r -w -i gpx -f %file% -x track,move=-1h -o gpx -F %1 pause
This is for Windows Vista/7 installations
Drag and drop the file you want to change the time on. It will create a backup of your file and shift the time for you.
Alternatively you can download the file here.