This year it was massive. I would try an organic insecticidal soap again, and the next day begin a process of spraying each plant, each day with as strong of a stream of water as you think your plants will withstand, making certain to spray the bottoms of the leaves. Mites can reproduce each 3-7 days, so it is critical that you spray on a daily basis until the problem is under control. Dry air encourages spider mites to breed so anything you can do to increase the surrounding humidity will help you in your 'mite fight'. Keep in mind that spider mites are NOT insects, so insecticides may not do any good at all, so be sure that the product you use is listed as being effective against mites, and follow the directions on the label.
Mealybugs look like little white tufts of cotton so are often mistaken for a disease.
They are normally found on the undersides of leaves or on stems at the apex of leaf joins. The white, waxy coating protects the insects from sprays, making control difficult. Touching each insect with a small brush or Q-tip dipped in alcohol will kill them, but the babies are very small and often overlooked, so a recurrence is possible. Systemic insecticides may work. Diazinon is effective as long as the mealys are thoroughly wetted.