Replacing the insulation or the leaky pipe?...I would have the leak fixed first by a landscape type outfit. The insulation can be done by a handyman or a insulation company. depending on the level of water it would also be wise to have the space checked by a mold inspection company.
If this insulation is stapled to the flooring above the crawl space your best bet is an insulation company as KMS suggested. I would look into your insurance company as well. They may cover this type of loss. In any case you need to remove the moisture soaked insulation asap to prevent any mold development.