How can I update my existing world map in Minecraft? [duplicate]

Solution 1:

These new biomes will only spawn in freshly generated, brand new terrain. Anywhere you've ever been before will be already generated.

What I'd recommend is going a few hundred blocks away by Nether. Every 1 block in the Nether is equal to 8 in the overworld, so you can get 8x further away in the same amount of time.

Keep looking. Horses are relatively rare and can only spawn in plains/savannahs. The mesa/flower forest/other new biomes have a fairly low spawn rate, so even if you go far away it could take a while to find.

If you have updated your Minecraft to the newest version (currently 1.11.2) by using the launcher, it's just a matter of looking hard enough to find the stuff you need, in areas you haven't even loaded yet.