First, congratulations on passing your Grade 8!
To take the piece further, think of the larger phrases and where they lead. There are a lot of subtle articulations that give the piece some spice. In the case of Beethoven, it is also the absence of an articulation that is an event in itself. All these articulation fit into the larger phrase, and can be drawn out to give the piece definition.
Try not to drop your hand to the edge of the keyboard when only playing white keys. Keep your hand over the keys and ready to play.
Topic: ABRSM Grade 8 Beethoven Sonata Op.79 1st mv