I just thought of something.

I think I know a way for lars to get off homeworld.

Now that Steven is on earth, he has a direct portal to homeworld, but lars cannot go through his own portal, but I have an idea on how he could get home, with some help from the crystal gems.

Here is my idea, Steven can go and grab peridot and take her to homeworld, Steven can put on a disguise, or have Connie and lars go as backup to protect peri from robonoids, peridot goes to where she got her limb enhancers I'm she needs them for the plan to work. Anyway, she could get/steal her some of the robonoids she sent to earth that repaired the Galaxy warp, have lion wait at earth's side of the warp, send peri to the warp via lars/lion, and have her fix it, the off colors come up while peridot programs the robot, she yells its ready and boom they all step on and go to earth.