How do you deal with low threat ranges?

I'm not really counting the +2" threat on SPD 4 models to be a threat increase, as most things in the game (or at least in my meta) will threat at least 10". Coming from my Ret privilege side threats start at 11" and routinely are in the 13" or 15" range, and we're hardly alone in that. Karchev, Strakov1, and in certain matchups Zerkova1 will be able to get around this limitation, but basically everyone else is on the slow side or barely comes up to parity.

I think part of my problem is not understanding when it's ok to throw my Shocktroopers/ a sacrificial jack away on a charge. I can tell that it's useful and really helps jam things up, but it's become so ingrained in me that charging shocktroopers/putting a heavy in charge range of someone else's heavy = dead models that I just don't do it. Plus they rarely hit hard enough to make it worth slamming them into a heavy. Thoughts?

Khador has a couple things we do to mitigate long melee threats, without even factoring in our warcasters.

The most important of these, in my opinion, is choosing how to receive enemy charges. Using your ret models as an example, most of those 11" threat jacks are only threatening 11" on a single weapon: the smaller blade is a 1" reach and only threatens 10". So if I positioned my warjack at 10.1" from yours, you'd lose out on an entire attack against me. Also, forcing your opponent to charge you will often make them lose an attack (spending a focus/forcing a fury to charge) which is a good thing. Crunch the numbers to make sure it's likely you'll survive, bring mechaniks, and counter-punch. Placing your warjack behind on obstacle/obstruction puts his defense up to 12 in melee, which will often yield a missed attack when the enemy comes in on him.

The second thing we have going for us is some surprisingly long gun ranges: we have the single longest gun in the game (Victor), and it's fairly closely followed up by things like Conquest, Behemoth, Rifle Corps, etc. My personal favourite is the Decimator: his 10" gun seems short until you factor in Beat Back. Beat Back forces the enemy to commit further into zones (or risk being pushed out), which shortens the distance between them and your front line. Used correctly, this effectively increases the threat range of our entire army.

The third thing we have going for us is how cheaply we can get models on the field. For 3 points we can get 4 mechaniks, and with their field allowance of 3 that's a total of 12 for 9 points. Winter Guard Infantry can be bought at 10 for 10, and have fairly easy access to tough. In Jaws we can get kossites at 11 for 10, or 7 for 6, and they have def 13 and Prowl. Putting a bunch of bodies in front of your warjacks forces a larger commitment from the enemy to actually get to them.

We have a fair bit of access to stationary, knockdown, etc which forces the enemy to shake the effect, which in turn lowers their damage output when they come in.

We have decent access to rough terrain, which forces the enemy to invest in pathfinder. Making a hordes player Rush his model prevents him from putting Rage on it. There are a fair bit of warmachine armies that lack pathfinder for their heavies altogether.

There is something very wise in here that I hadn't spent a ton of time thinking about (bad player that I am)

An advantage of someone like Sorscha1 - with proper positioning, is that you can force your opponent to spend a focus/fury shaking....and hopefully another charging.  

There are SOME things that can one round a Khador jack with just initials and maybe 1 or 2 buys but not THAT much.

And this is also why I'm gathering that including mechanics is a good thing, especially for Khador. As if it doesn't kill your cortex you can repair up and get ready to hit back.