Often, the box and platform are the first parts of your pointe shoe to "give". Applying Jet Glue to the shank and inside (never outside) of the box and can prolong the life of your shoes, if they're otherwise still in good shape.
You could try using any old glue, but Jet Glue is a professional grade glue which dries fast and extremely hard. It may seem a bit expensive, but you only need a few drops to do the job, so one bottle will go a very long way. A more economical alternative is Hot Stuff glue, which is becoming more popular with dancers.
Some dancers line their shoe with Jet Glue while the shoes are still new, to prolong their life. If you'd like to do the same, break your shoes in to your liking first - the box will be rock solid once you've added the glue, and you'll have no hope of shaping it to your foot. Also, be sure the material is nice and flat before you add the glue - any wrinkles will also set rock hard and give you blisters.
Warning - be very careful about spilling it where you don't want it. It can be removed from satin with nail polish remover, but it will leave marks.