I haven't been using my laptop and iTunes for quite some time and the apps that are on there are way out of date as I have done some house-keeping on the iPad and iPhone over the last months and deleted loads of apps I don't use.
If I were to delete all the apps from iTunes and then do a USB cable sync with both devices would iTunes tell me that the apps were missing from iTunes and upload them from the two devices; and then be in sync again. i.e. remove from iTunes the apps that I no longer need.
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