[hec]

Hit the Personalize icon from the Home screen, select a different Scene and then switch back to the one you had been using; it'll refresh all the icons.

Also, you could use a handy, free widget called Multicon Widget, which allows you to fit more shortcuts on the screen, and it seems to cache the icons, preventing them from changing to the generic icon in the first place.

BTW, I nest the Multicon Widget with another called Folder Organizer, so each of the four shortcuts that I can fit into the space normally taken by a single one opens a folder displaying all the apps I have categorized accordingly. So now I never have to use the app drawer; once I categorized all my apps (e.g., games, tools, internet, etc.), I simply open the folder for that category, and I get a window showing all corresponding apps.