If you have a large WPA dump file you need to remove the excess data. You can do this with WPACLEAN utility from the aircrack-ng suite.
Source and/or binaries are available at Aircrack-ng.
$ ./wpaclean small_capture.cap big_capture_file.cap
big_capture_file.cap is the file you want to reduce, small_capture.cap is the result file.
Once done you can upload the file 'small_capture.cap' which is smaller.
You can send us your capture file by email : firstname.lastname@example.org, we'll do it for you.