If you're using something like Perlin Noise for the terrain generator, there are a number of ways for converting a basic noise field into a tiling noise field.
The simplest IMO would be to blend the value for the current coordinates with a copy shifted over by one and work using modulo math.
F'(0) = 1 * F(0) + 0 * F(-1)
F'(0.25) = 0.75 * F(0.25) + 0.25 * F(-0.75)
F'(0.66) = 0.34 * F(0.66) + 0.66 * F(-0.34)
F'(1) = 0 * F(1) + 1 * F(0) // Matches with F'(0) = tileable!
That will keep the planet from having seams at the poles, and you just have to take care with the math when the player is near the pole and looking over.
If the worlds are reasonably large, that shouldn't be a problem for gameplay since even 16 bit coordinates would make a circumnavigation in the buggy an epic week long RL marathon if you don't stop for anything and have more gigs of ram than you can shake a stick at.
Smaller worlds would need the plants to regrow at least, and probably a new drilling rig setup to get more water.