Many users are driven away from this mod all the time because of issues updating their worlds. Here are some tips so that you don't lose progress.
Back Up Your World!
This is the Most important step. Go into your .minecraft folder and find your saves folder. Inside this folder, there should be a folder named the same thing as your world. Copy this world to a different folder so that you have a backup. This way, you can have infinite copies of your world even if you ruin one.
Before Updating Mod Version
Put everything in your inventory in a chest. Leave any mounts where they are on a lead, because mounts have been known to de-spawn. Sleep first so that you don't get attacked at night by hostile mobs. Then go somewhere in your world where you don't care about anything from the Mod being deleted.
After you have updated, go back to where you left your items and mounts. They should all be there, and you can continue playing!
LotR Mod & Wiki Help
Mod Installation •
Compatible mods •
Creating a modded server