While you have your nozzle is soaking you can use a pipe cleaner or similar to clean the passage from your paint cup to your nozzle. You may still have gunk in there which is re-clogging your tip.
Try back flushing also when you are cleaning or changing colours. With your air cap on, hold a rag or your finger gently over the tip and pull back for paint while you have your water or solvent for cleaning in your cup, this shopuld direct air back up the paint passage way and into the paint cup, this blows old paint and gunk back into the cup. Tip this out and repeat with cleaning fluids again until it stops then just blow the fluids through for a bit to finalise cleaning.
hth,
Mick.