Feature>Copy>New Refs>Independent>Select the feature. Then use the same dimensions. Say you have the feature on the right of the cube and want to copy it to the top. When it asks for the alternate sketching plane > choose the top plane. For the horizontal reference choose the corresponding horizontal reference (say, for top choose right). For vertical reference, choose the corresponding plane (say, for front plane choose the same). Then give ok. It is better if the sections are drawn independently without using Use Edge-otherwise the corresponding edges have to be selected using alternate references.