Buy some 3/4mm amsteel and just make your own replacement. Take one side off, make 2 bridles the same, then replace first one and then the other. Bridle ends can just be granny knot loops, they do not need to be sewn. Use 2 knots close together if you are not good with knots (Fig 8 knot would be better).
You can but the line here
www.kitepower.com.au/Its a good idea to replace the pulleys as well, they are cheap, and if the line has worn out the pulleys should be replaced too.
www.kitepower.com.au/cabrinha-pulleys-w-pigtail.html
