Who would have transfered his consciousness though? Doesn't seem to be the sort of thing you can do to yourself...
Data could have helped too
Maybe there was already a lot of Soong in Lore. And Soong was embarrassed how Lore turned out.
It wouldn't seem believable that Soong could have been married at all if he'd been anything like Lore. Nah, it always struck me that Soong was a pretty decent guy, who's big mistake was that he'd made Lore too well, stronger than a human, smarter than a human, tougher than a human, & more emotional than a human
That's always what I figured about Lore. Soong had made his emotions too powerful. His hate, resentment, jealousy & obsession would overpower him, & he'd do terrible things, which in turn made him feel he was a terrible person, & in turn made him identify himself as such, creating a cycle of bad behavior
When Soong admits he's dying, Lore has a genuine emotional reaction that is not evil, but more like saddened, & concerned. So it's apparent he has good emotions too, but his bad ones so often consume him, making him behave badly, that he identifies himself that way. Besides, even too much of a good emotion is bad. That's Lore's flaw, too much emotion
This is why Data was given none, until Soong could correct the problem, or fine tune the program, but by the time he creates Julianna, it appears he's sorted those problems, & perfected the transference technique, & could then be reasonably sure that transferring himself would work, & he'd then have time to help Lore, & perhaps B4 & the others too
But he chose not too, at least not that we see, & we sort of watch Data see Soong die, & I presume that transference would have to occur before death, & doing so would leave the former body dead or evacuated... perhaps
In all likelihood, he didn't do it, & it would have been nice to know why not, like perhaps, by the time he'd thought about it, he realized that what he'd done to Julianna was wrong
The Soong in the hologram that Data sees is much younger than the one Data encounters. Perhaps in all that time, he came to believe that what he'd done was wrong, hence why he didn't tell Data & Lore about her, on his death bed
That's the only explanation I can come up with