Have you set up a special and have now decided you want to continue the special past the original end date?  
Bring up your items in Maintain Products in Bulk. A good way to bring them up may be using the special start and end date:

From the Main Menu:

  • 2 Stock control, 3 Stock maintenance, 1 Maintain products in bulk
  • F3 [Add]
  • F11 [Next Page] twice
  • Enter the specific Special start date and Special end date originally set up

  • F12 [Accept Details]
  • Your product list will generate
  • F6 [Set Prices] & P [Specials menu]

  • A [Finish date/time]

  • Add new special finish date
  • F12 [Accept Details]

  • F12 [Accept Details] twice and Y to change products
  • Your new special finish date will now be active