There's quite a bit you can improve on just from rerolling items you already have. First of all, roll for EP damage on both helm and boots; EP is (basically) all your damage, so any buffs you can give it go a long way. Other than that, remove all resist wherever possible. Monks get most of their allres from the harmony passive, leaving an extra primary stat for you to grab (harmony uses the secondary single resists, as opposed to the primary all resist).
As for your weapons, they NEED 10% cdr roles. U6 is kind of unique in that cdr directly translates to damage, as the more SSS you can get off, the more EP damage goes off, and therefore you clear faster. Cdr isn't limited to just weapons either; both rings and shoulders can be improved (+ paragon points), but the most noticeable upgrade will be from the 20% that you can get from the weapons. Just to add onto the cdr point, it also helps your survivability as you can become invulnerable more often.
As for new gear, ancient weapons are a MUST for immediate improvement. I went from ~50 to 55 just from getting them both to be ancient. For armor, ancient chest, legs, and boots are a huge defense increase simply due to the large amount of stats they give. Your current chest has some unfortunate rolls, as you really want to have vit and %life or armor on top of the elite dmg reduction, and you don't want to have allres on anything if you can help it.
Some final points to consider: secondary resists MUST be taken into account when you're comparing gear. A 1% toughness increase with no secondary resist is NOT necessarily better than gear with a secondary, as the comparison can't take harmony into account. On top of this, ancient armor can roll higher secondary resists, making them even more valuable. You can also start grinding out a good hellfire with cold%, CHD, and a socket. Preferably with the Beacon of Ytar or Harmony passive. Finally, start grinding up your gems, both legendary and normal. Use the cube gem conversion recipe to get the emeralds you need to max out your chest and pant slots. Higher GR will also require you to use bane of the stricken, so you can start leveling that as well.
Hope this helps!