Remaking it from scratch? That's actually what, as a matter of fact, I already guessed was the only way to get it done. The animations, which I believe might need some rework as well on some level, the sounds and a few more assets were most likely the only things I would have saved from the original author's project. Adult animations and sounds are, in particular, one of the hardest resources to find when developing an adult game... definitely not the kinda assets we can find on FAB, right?
If your going to start from scratch, a few thing to consider.
Dropping the real life locations. It's a fun gimmick but didn't really work, apparently the garden centre near me was actually a whore house! creating a sims style area's would allow much more control, stability and let you create environments tailored to the game, this would also allow theming them, think lifeplay medieval, sci-fi lifeplay.
Consider keeping the sex in the main game routine, Lifeplays way of making sex sort of a mini-games disjoints it from the main gameplay and causes all sorts of problems with the scenes.
DO NOT break relationships into different types of people. In Lifeplay relatives and no-relatives are completely different beings, again this caused major issues.
Make all furniture contain activators for the actors, look at how bethesda does their furniture. Then trigger sex scene's to these activators. You now have laying sex on beds, tables, rugs, sitting sex for chairs edge of beds etc, etc.
Shaders, use graphic shaders to hide body parts, and underwear. Each item of clothing has a shader that blocks the poly's underneath it. So a bra would block the poly's of the breast, a dress would block the polys of the bra and the breast. It is actually fairly easy to do, makes the clothing all fit better, looks better, and costs almost nothing in performance.
Doing these things would however mean it was no longer Lifeplay, but it would also be far superior.
Lastly a couple of other things to think about.
Get a group!!!, You need two coders, an animator, and a 3D modeler.
Do not be greedy Patron destroyed Lifeplay!
Also your comments on assets are not correct, most people who can do basic animation, could make sex animations. They are not that hard, look at loverslab on the sims pages! also I believe some of the sex animations in Lifeplay were from Skyrim/fallout. Sounds, contact someone who plays with AI speech. The sounds and speech could be made in a couple of days, again this isn't difficult.
