Try this to reprogram the UP and DOWN arrow keys (the LEFT and RIGHT should be correct as is):
1. Press and release TV
2. Press and hold "P" until the remote blinks twice
3. Type 994
4. Press and release "P"
5. Type 038
6. Press UP ARROW
The remote should blink twice if it accepted the programming
For DOWN arrow, repeat the above steps, and use 042 for step 5 and DOWN arrow for step 6.

If those worked, you may want to try a couple of other keys that are also not preprogrammed in the 15-2133:
TUNER = 104
PIX SHAPE = 106
RESET = 244
AUDIO = 247
CAPTION = 121