Hang the flea collars where they won't come into contact with the plants, soil, or water. The fumes from the collars will ward off the aphids, but if the stuff in the collars dissolves into the plants' water supply, there'll be trouble.
Acephate (AKA Orthene) works best and is safe on just about all CPs, but is toxic and can't be used on plants that live in your home. If you apply it, the plants must be quarantined to the outdoors or a greenhouse for a month. It's the active ingredient in Ortho Systematic Insect Killer, available at most hardware and garden stores. Orthene is nice because it not only kills the bugs on your plants now, but it will kill any bugs that feed on your plants for several weeks after application (that's what the 'systematic' means.) There are some other artificial insectides that work on CPs, but they're just as toxic and not safe for all CPs so I don't pay them much mind.
Pyrethrum is an option for some plants. It's a natural derivative of chrysanthemums, so it's safe indoors and even safe on fruits and vegetables (after washing, of course.) The downside is that it is topical, meaning it only kills the bugs that it touches. It often needs several applications to completely treat an infestation. It is harmful to the tentacles of Drosera (it kills the tentacles but the leaves are left intact) and the pitchers and flowers of Sarracenia, and I don't know how other genera react to it. However, it's the only thing sold as insecticide I've encountered that's both safe indoors and recommended for CPs.
I remember hearing that a dilution of rubbing alcohol or apple cider vinegar work for many pests on CPs, but you should do some research on that before you go hosing your plants down. Those methods would also be safe indoors, and possibly cheaper than commercial insecticides. And don't forget about drowning - you can submerge VFTs and many Drosera for a few days in RO water to kill off the bugs. Just make sure to completely cover the plants so the aphids can't climb to safety - a few months back I tried to drown a flowering D. spatulata without submerging the blooms and ended up with a dozen flower stalks of aphids.
Best luck,
~Joe