Tricky question. If you're really dead set on having the reavers in then I'd suggest considering the following. Rather than cutting an entire unit and replacing it, consider slimming units to add an extra one in, that way you get maximum target saturation, and more focused units.
Trueborn - Are the shardcarbines genuinely worth it with 18" range? Can you survive with just the cannons at 32"? That can save you 22 points, there's one reaver..
The beast unit is a lot of points, would slimming it down fractionally impact its effectiveness all that much? Dropping one Khymerae and one Flock gets you another 27 points
The Ten man Kabalites. How many times per game do you actually get to fire that dark lance? You really have to be absolutely sure its worth having for 25 points... Otherwise, if you're sitting in the backfield camping an objective with them.. then do you need the blaster? I personally can't see a good argument for having both in the same squad. I would also consider dropping both... Blasphemy I know, but that would be another 40 points.
I love me some Night Shields on my ravagers as well, but in a pinch you could lose both for 20 points.
Your Duke's wyches. Are you definitely going to assault a vehicle with them? If so, how are you going to deal with your HQ potentially getting stranded and shot to hell? I'd rather have him, and by extension them, in cc with another unit. So I'd consider dropping their HWGs, I'd also consider dropping a body as well. That would be another 26 points.
If you do all that you've got the same number of units, but an extra 135 points.. That'll get you six reavers, but no heat lances yet.. I'd have a long hard think about that big kabalite squad again.. Ten naked kabalites in a raider, or five in a venom.. Essentially you're going to have to ask yourself whether you think two heatlances will outperform two dark lances.. If the answer is yes, then drop the raider and five bodies (you can even keep the blaster!).
Hope that's of some help