In this second part we get to know some new ideas, especially starting at bar 142. It`s like a huge and steadily increasing flood of notes, but instead of a real climax it suddenly aborts after the ascending arpeggio (around bar 178). It's repeated, but the "flood" is over. There is no climax, on the contrary, we now get to this very intimidate piano passage (192-211), nearly the only rest place in the entire movement.
I would think from bar 142 you wouldn't aim to steadily increase. Instead it is trying to set up a contrast between two intensities of the melody. As you see, he plays the RH melody with one note to start, then contrasts it with octaves. The octaves reinforce the melody and naturally echoes what you play at a louder intensity. So from bar 142-157 highlight this relationship, controlling to a softer sound when the RH plays single notes and then supporting an increase of suond when octaves play. This to me is the basis for interpration here.
Bars 158-167 should sound more legato so that when 168 appears the double tailed rests beethoven writes is highlighted and the sound is more detached, another contrast. As you approach 176 you should really broaden what you are playing, slow down a little, but think about broader sounds more than tempo slowing down.
Then when finally you reach bar 176 you hold the sustain down the entire time and the upward arpeggios are given full length making the whole piano vibrate. This sound almost echoes through the room when you release the entire sound for the whole bar rests. The two ff arpeggio sounds are then contrasted with softer p, dinimishing, this which should allow listeners to percieve each note a little clearer, not as one whole body of sound as the first two ff ones.
The slow down is so important as you see entire bars played with just one note from 200. This highlights yet again another contrast when you move back to the original theme. The contrast between a huge slow down then back to a brisker tempo makes what you play sound much more exciting, even when it is played at pp. If there is no slow down then it is so hard to make this return encouraged.
Beethoven always highlights contrasts in sounds throughout his music. I guess that is why he was such a good writer for piano because he utilised what it could do. You have to ensure you always search for what part contrasts one another in Beethoven's music.
When I peform this piece I never do the repeat, also I don't do the repeat in the First movement of the Pathetique when it returns to the second page. I have also heard the same done in other peformances/recordings. I don't think it is absoluetly necessary to do the repeat back to Bar 118 even though the autograph says it. I personally never liked it also. I vaguely remember my teacher saying to me that in examinations you do all the repeats but in pefromances you dont have to. So I guess it's up to your own prefference.