the salt will draw the water out of the pretels and cause them to dry out

the best thing to do is slightly underbake them with no salt and frezz them

when you want to eat one take them out wet them and put on the salt the wet surface will cause the salt to stick then warm them in the oven for a crisp crust or nuke them in the microwave for a soft doughy crust.

This has happened to me so often that I finally gave up trying to make pretzels.  I gather that now you can buy something called pretzel salt that doesn't dissolve and make the pretzels go mushy.  Check out kingarthurflour.com.  They had it at one time.

I have the same problem with the salt melting too.  I use kosher salt.  Will have to look for the pretzel salt.  My solution right now is to sprinkle on a healthy portion of grated cheddar cheese and bake.  The cheese has plenty of salt in it so you don't need additional salt.  After we are done munching  pretzels on baking day they go into the freezer.  Reheat by nuke for about 30 seconds just to thaw a bit (don't want a hockey puck) then into the toaster oven on dark toast (about 2 minutes) to crisp it up again.  Bring on the spicy mustard and yum!

I use KAF pretzel salt all the time and it doesn't melt.  However, pretzels are like bagels; they don't keep well.  I make and salt them with KAF pretzel salt and just as soon as they are cooled down freeze the leftovers.  One cycle in the toaster oven on light and they taste fresh baked. 

Thank you everyone for your replies above. I will try the freezing, toasting and pretzel salt recommendations.