If you wish to start a new term, keeping the same students then it is advisable to follow these instructions: 

http://www.1st-class-software.com/cgi-bin/fom.cgi?file=31

If you wish to start a new term/year keeping the same activities then follow the instructions below.

1) Open last term/years grades file.
2) Choose File-SaveAs and save the file to the name you intend to use for your grades file this term/year.
3) Now delete any information you do not wish to have transferred to this term/year.  (ie.  Delete all the students but leave the activities.)

Now you can continue to use this new grades file for the new term/year.