when you get to your master's degree, you have a level of flexibility that you might not have had at the bachelor's level. for one, they don't argue with you much over your program as long as you and your teacher have agreed upon it. we can suggest, but your teacher is really the one to listen to! he knows what you play best. you don't want to play anything that you don't interpret well.
for instance, for me, i'm still a total dud when it comes to chopin, but i can play bach preludes/fugues, suites pretty well and from memory i might add. it's something that you just have to figure what makes you nervous and AVOID it for performances until you are comfortable. chopin etudes make me way nervous, but i can play one alone at night at 1:00 in the morning ok. bach, i just feel comfortable with.
for me, saint-saens is my saving grace. i can play saint-saens way easier than chopin (but i'm still working the chopin). if i were even to do a grad recital, i'd try to talk my teacher into my ability to play saint-saens or faure because i personally feel like i can handle it better.
of course, you can't get away with an 'easy' program for grad work - so spend A LOT of time on your 20th century piece. if you do well at one or two of these - you are assured success. this is where the bulk of your practice will pay off in dividends, imo. people at the grad level have to play something that is not 'mainstream' to impress the teachers and audience who have heard 'everything' before.
be creative and still according to your talents and interpretive skills. listen to lots of new music that you haven't listened to before. look at some master's recital programs and copy some ideas? you have to show a progression and maturity level above the one you obtained at the bachelor's level. more intricacies in the playing - more difficult harmonies - more nuances. only your teacher can get this going - unless you are a good listener and go to a lot of concerts or listen to a lot of good recordings.
i've found, too, that reading journals has stepped up my limited understanding of the levels of depth of musicianship. first, we worry about notes, then memory, then interpretation - but at the master's level it is fine tuning (nuances and not anything basic anymore). this is why keeping at this level requires a lot of practice (speaking to myself) this is 6+ hours a day to stay level with other pianists. 3-4 makes you still at the bachelor's level. it's a real trade off. should we practice, study, or eat??? i say, practice practice practice - and then study and eat together. i always get food on my papers. (i can't practice this much right now, but am getting better).