Excellent advice from Steve, as ever. Just a couple of other points.
Note that much of this piece, including the problem section, is in Db. I don't think this is purely fortuitous, as it gives access to the black keys which require less distance in movement to play, and this has to be to your advantage. Minimum movement = faster repetition. Incidentally, as in this piece, I think Liszt often achieves a wonderful warmth in the key of Db, q.v. his studies
Un Sospiro and
Harmonies du soir.
In general, you can also play repeated octaves on the black keys with alternating fingers, e.g. instead of:
5555
1111
use:
5454
1111
or
5434
1111
This assumes you have a good hand stretch of course. In this piece the repeated notes thicken out to four-note chords so that wouldn't be possible throughout.
Schubert's song
Erlkönig has repeated octave patterns throughout and is quite notorious among accompanists for its taxing nature. It looks fairly straight-forward, but just try it:

The complete music of the song is at
http://www.dlib.indiana.edu/variations/sco...046/index1.html under Ausgewählte Lieder.