I left the post before this because it is partly right. If you put LBT lube into a sizer without cleaning out any previous lube of another brand, you can be assured that the bullets which come out with some of each lube will not shoot accurately. This because drag on the competitive lube side will cause the bullet to cock in the barrel and leave with a wobble.
But the answer which was asked for was a simple fix for the commercial bullets. Simply wipe a thin smear of LBT blue soft over the existing lube and your leading problem will go away. To apply the lube, wipe a little lube of the stick with ONLY the index finger of your master hand and use this finger alone to smear the lube. Bullets must be fairly warm or you won't be able to smear it on easily. If the bullets are lubed with a very soft lube, so that it slips and bunches when apply the smeared on LBT, the only solution is to melt it off and wipe your lube on the bare bullets.
If you want to replace the lube, with LBT by running them through a sizer, melt the lube off by laying on a folded junker towel, or layer of paper towels in a cake tin and warm in an oven till the lube flows into the towel. When cool, apply your new lube.