A solution of 1 part bleach to 20 parts water will kill algae spores and snails/snail eggs.
Dip the plants for up to 2 minutes in the solution, then rinse in a bucket of triple dechlorinated water.
The more delicate the plant, the less time you should dip. Ambulia and cabomba are delicate...don't dip them more than 20 seconds.
Expect your plants to look kinda beat up for the 2 weeks after the dip. They'll take some damage, but will come back as lush and bushy as before (if your tank provides an ideal living environment)