Help with gps utility for army walk across UK

hi, im planning a walk from lands end to john o groats 1200 miles across the UK
leading a group of 8 men from my TA unit, to help with this ive manualy imputed a large amont of gps data on evertrail.com
but little did i know when you export the data as a gpx it seems to format it all really
badly meaning other gps aplications can't read it.
its too big to reformat manualy so ive been looking for a program to do it,
the only one ive found is gps utility if i open and resave the gpx with it fixes the problem
But . . . because i haven't spent the $60 for the full version it will only do this for a tiny part of the file.

so i was hoping somone could offer me some advise to fix this file ive spent so much time on, or maybe a way i can use gps utility for a job that would only take 10 seconds . . .

Regards,
Sam Andress