The problem is caused usually from leaving the inflate plug in place for long periods of time. As mentioned above, take the plug out at the same time you deflate the kite and this will avoid the issue at all.
As for a quick fix, try this :
-boil the jug, and fill a bowl up with some boiling water.
-dip the valve stem
only into the boiling water for about 30 seconds
-grab some zip ties and zip tie around the valve stem tightly
-leave zip tied over night and remove the zip ties the next day.
IMPORTANT:
when you dip the valve stem into water, make sure you do not submerse the entire valve and bladder, this will separate the valve from the bladder and then your more stuffed.This process will restore the opening size so that the plug fits back in nice and tight.
Happy days!!
Joe
