heres some tips:
you could raise the heat very slowly to about 80-82 degrees to speed up their life cycle. this would need close supervision of the infected goldfish (tropicals will be fine) for rapid breathing from having less dissolved oxygen available. increasing aeration should help counteract that.
very thorough gravel vacs for the enirety of each waterchange. or remove most of the gravel to the point of only 1/2inch deep. try not to have any stagnant spots in the tank as well. water should be flowing freely around every cubic inch of space.
keep the filter floss very clean and flowing freely so that the prazi bits are not being trapped in any filtergoo.
try upping the amount from what the bottle suggests. you can very safely go 25-50% more at each and every addition with no side effects whatsoever. ive double dosed the stuff and none of the fish in the tank even noticed. i also noticed that it worked much better.
an extra tip for breaking the prazi down:
ive figured out the best way to break the prazi down while pretty much eliminating all the shaking (give those jugs a break!

). find a 1 gallon jug that allows you to easily slip your forefinger into it. fill the jug halfway with some tankwater. add the prazi and shake for about 5 seconds (again, the jug, not you!

) one the bubbles clear a bit and the unsaturated prazi float to the surface, fill the jug up to about 2 inches from the rim. now, for this part you can use a rubber glove. but the prazi is nontoxic and your bare finger will be fine and actually work better. just put your finger into the jug and start pressing and rubbing the bits up against the inside of it. after a few minutes of this, the prazi should be very well dissolved and ready for dispersal into the tank.
i hope some of these suggestions will help you. i know every little bit helps when dealing with these persistant little bugs. <_<
good luck erika!
paul