Not enough info to really say.

Are these growing indoors, or out?
And, if indoors, what sort of light?

What size containers are you using?
And what type of potting mix?

It *is* possible for the plant to
re-grow leaves....as long as it's not
already at death's door.

Josh

I had same problem (Aphids) and Used clothes detergent with
oil and water solution and I did kill the Aphids, along with my Red Savina's (almost) I first watered or sprayed the plants
hoping to rinse the solution back off, then used Miracle-Gro
transplant solution when I watered them a couple times the first week and they are all budding again on the tops with some flowering.. :) I have been told that stressing the plant out it will yield better, I think I took them as far as they could possibly go...we'll see..Good luck,

*Don't use too much concentrated detergent*
just so happens, the brand the wife bought was supposed to be Concentrated x2, guess I should have read the bottle..

Depending on the type of soap and ratio I think that is what hurt the leaves. It's actually soap not detergents that will kill aphids. I use murphys oil soap at a ratio of 2 tsp per litre. Don't spray midday only in morning or night. After about an hour you can rinse it all off just in case. Make sure you get under all leaves and even the stems. If you don't have many plants you can just squish the aphids or spray them off with water. All the best.