>>5258241My tried and true method
First dust the figure with a paintbrush, in pic related I'd reccomend the "mop" or "flat". Be sure to get into crevasses and under armor and joints and such
Canned air duster followup
and then gently wet a wring out a paper towel with warm water, give a gentle wipedown. Let the figure sit out for awhile to dry.
Voila, good as new