1, not making a server a super free item mall, a little work is a good thing.
2, if you're going to go with EP5+ modify mage skills so that the mages are again the highest damage dealers.
3, make sins/rangers good again, 1 you'll have to modify added damage by their skills since their 3x multiplier is a 90 second cool down, maybe change some of those 150's and such to 400's, also give more reduced defense with tetanus (I think that's the skill).
4, remove pottability of Dark Panic and increase the percentage slightly for evasion ascent, and I do mean slightly, maybe 3 percent. (still for rangers/sins)
5, It might be cool to add a small recharge timer (like, 5 to 6 seconds) for dispell pots. That would force people to use some skill in saving their dispell pots till certain skills have gone by before they pop a dispell pot instead of "spam spam spam spam spam". It would also make Rangers/Sins the king of 1v1 again.
6, don't reduce behemoth rage to 2x multiplier, because then guards/defs could be kind of underpowered by a bit to their fighter/warr counterparts, but somewhere between 2.4-2.6 would be more reasonable.
7, add mobs to the mix of PvP as an actual threat (there's a thread on this by me somewhere in the top 10 or so posts of this section, maybe read that)
8, limit the level for CTI, and make a 60 PvP zone. (again, assuming you're doing EP5+)
9, Add team and 1v1 tournaments on a monthly basis, that sh*ts fun. (I don't know exactly how you'll do the team vs. team one, but, I think it should be doable). Maybe you could add a super tiny priced "registration rune" that's purchasable in the item mall (and I mean quite cheap) that is a tradable item so people can buy one from the item mall or buy it off a player who donates (bam, you just made money without giving extra stats).
10, Dayfly, extend the cooldown by a butt ton, or, make the skill not last as long (I personally don't ever have problems with it, you can just run, let it burn out, and then you kill a bunch of them while they're too far out of their base to run back, but, others will bitch, so, might as well address it).
11, Maybe make different kinds of top level accs. Instead of there just being, you know, 25 stats to all, maybe there could be different versions, maybe one with 25 str, 25 dex, 25 luc, another with 35 str, 35 rec, another with 40 int, 30 rec, 10 luc, another with 40 wis, 40 rec.
12, Adjust the drop rate of things like lapisia so that you have an even supply for the demand requested.
13, Adding MMs, farmable items, and maybe some good gear for higher level pvp to the 30/15 zones might bring some life to them. Also, I think that you should have crit noss... But with a level cap of 15 and make it an extremely rare drop from one of the toughest bosses, that ways there's not much of it, but, it's only valuable to 15 pvpers, or GRB toons if they don't go the EB route.
14, I can't think of anything else so, I'll stop there.