"Some possible explanations:
-They didn't have the right or enough resources to make a second."
Yeah, and Christina Aguilera is concert master in the New York Philiharmonic Orchestra. If they can build 110 Santhanas juggernauts, they can build as many Lucifers as they want.
"-The Lucifer costs allot of mulla (or resources) and since it can be destroyed in subspace it wouldn't be a great idea. Not to mention it would collapse nodes and may be bad in the long run for them."
As I said previously, if the bugs can field 110 Sathanases and purposely sacrifice them to destroy a star (talk about wasted resources), they can build plenty of Lucifers.
"-There are more but the shivans didn't want to or could not get them to the area in which FS2 happens fast enough."
They probably didn't want to.
"-They lost the plans."
Almost impossible.
"-The Lucifer's shields couldn't stop beams."
BINGO! Now that the GTVA has beams, the Lucifer's main defense is useless. Besides its Shivan Super Lasers, it has no real weapons, so the Colossus or even a couple of destroyers would rip it to pieces.
"-After contact with the terrans in Gamma Draconis, a Lucifer task force would not work."
They didn't want to bring out Lucifers against an adversary with beams. The Lucifer is nothing more than a terror weapon, and once it's shields are defeated, it's much less terrifying.
"-They just wanted to blow up the Cappella star. And that was their plan all along."
I don't think Lucifers would be big enough to accomodate the gravity-warping thingamabobs
"-A combo of these."
Read my explanations.
"And of course this opens up more questions like, 'Did the shivans have Sathanas during FS1?', 'Is the Sathanas main purpose to blow up stars?'"
The Sathanas is probably a different sort of terror weapon that the Shivans use when their enemy doesn't get the message the first time around. Its main purpose is to scare the **** out of other races and destroy their fleets as well (that's why it has FOUR BFReds).