It may not be necessary to rewash them if you just have a few water marks. These only tend to form on the shiny side of the film, so lay the strips in turn shiny side up on something clean like a negative page. Then breathe on them as you would to mist up a mirror and then wipe them gently with a lens cleaning cloth. If the spots don't disappear, dab a bit of ethanol on the cloth and wipe again.