If you have a Razr Maxx that has been updated to Ice Cream Sandwich, the process of adding back a widget isn't quite the same as the How-To thread posted above. In order to put the widget back on your homescreen, tap the Apps icon in the center of the icon tray at the bottom of the screen (the circular one with the 6 dots in it). Then tap "Widgets" at the top right of the next screen, and then swipe until you get to the Kindle widget. Long-press it, and drag it to the homescreen of your choice.
This is all assuming that you mean the widget, not the shortcut icon. If you just want the shortcut, then touch the Apps icon, make sure it says "All Apps" on the top left of the screen, swipe until you find the Kindle icon, then long-press it and drag to the homescreen.