After many kills in The End, it is an easy encounter when you come in with the proper equipment. The proper equipment being bow and arrows (lots of them), sword, and full armor. Also all items enchanted for the most benefit. I started thinking of ways to make this encounter harder. Here are some of my ideas.

Spawn other mobs (creepers, skeletons, etc)
Multiple Enderdragons
More damage taken when hit by mobs

What would you like to see?

Multiple enderdragons. Nothing else in the list, haha!

I only have a problem with the actual encounter not being as difficult as it sounded like it would be. It seems ludicrously easy to me after killing the dragon twice, and it seems much more an issue in terms of Minecraft itself rather than something we can change easily. I suppose it's also true that you have outfitted us for the fight, Mono, but even without that I feel the battle would still be easy, just would take much longer. I don't recall taking much damage during the fight, only dying from Endermen once the first time, which all you need to do is ignore them and you're fine.

I regret that the dragon itself was not made more difficult.

Endermen become automatically hostile if you're too close to them in The End. It's too easy to avoid Endermen. (You know how many Endermen there are, so not everything is immediately hostile.)

I beat the enderdragon also now, but how long does it take to respawn?

Monoman has to reset the end manually.

He reset the server but the dragon didn't come back.

Maybe he left the end map as it was. By ‘reset’ i mean deleting the existing one and let the game create a new. By ‘reset the server’ i hope you mean that he restarted it! o_o

Yes he restarted it. I just fought the enderdragon a second time

I'm enchanting a full set of armor and tools to level 50. I already have the full set of armor enchanted at 50. I have a special plan for this

Level 50 doesn't mean good, level 50 can suck pretty badly. 1.3 released in two days however (one month later than your post) will have maximum enchantment "level" 30. Level 30 gives a better chance of two or more enchantments now.

Tell us what they're actually enchanted with.