Unblock an omitted bloque

Once one omits a bloque, but later changes his mind, can he go back and unbloque it? Does he/I need to delete a saved file to do that?

The skipped block will have a little marker on it like a slash “/”. Also, the “skip” button at the bottom of the screen will now have a box around it. Click on the skipped block and then click the skip button again. The box and / will disappear and that block can now be recorded.