How to Properly Update a FTB Server?

[JPandaGamer]

Hello, I have been hosting a small server for my friends and myself on the 1.0.3 Unleashed pack, and now that it's formally out, we'd like to update. So far, I've tried deleting the old mods and coremods folders and replacing and configuring them, replacing every old file with the new ones, running a new server then swapping the worlds, but the old world won't load properly.

I'm sorry for asking such a stupid question, but I'm new to hosting servers, so I'm not sure what to do.
Also, yes, I have googled how to update FTB servers, but after trying all the things I was told to do, still, I got the same problem.

 

[Vauthil]

A pastebin of the server log from when it fails to load the new world would be immensely helpful right now in trying to pinpoint what's going wrong.

 

[JPandaGamer]

I am hoping this is what you mean by the server log. Also, sorry, still very new to being a server owner
http://pastebin.com/7x8WX6V4

 

[cjm721]

Either the out of perm gen space caused the crash or your missing part of a mod. Try increasting the perm gen size first then come back and tell the results.

 

[JPandaGamer]

I'm sorry, but what is perm gen, and how do I increase it's size?
EDIT: I just went into google and tried what the first few results said and added -XX:MaxPermSize=128m to the ServerStart batch file, but that didn't fix it, I've also bumped that number up to 2048, still with the same results
EDIT2: Actually, I went ahead and looked more into the perm gen stuff and found out I had it misarranged in my batch file. That fixed the problem.
Thanks for the help