[daotoad]

If you wanted to take this a little further, you could cover the "display" with heat erasable ink like is used in a Pilot Frixion pens.

This ink is interesting in that it fades when heated (60 C), but darkens when cooled (-10 C). In between those temperatures it is stable.

Thus you could have one loop that is continuously reused. Not sure how many cycles you can get before the ink degrades.

[gmueckl]

I like that idea. The printing process should probably be inverted: cool the paper as a whole to darken the whole sheet amd use a small heating coil to erase.

[afandian]

Or thermochromic film

https://en.wikipedia.org/wiki/Thermochromism