Lets ask the Deep Rot what the current tech of the mortals is like.
There's mass artifact crafting. Either crash the economy of the holier-than-thou empire with discount artifacts (If nothing else, bandits will find some), or just create a little shop that teleports around and sells just the right artifact to those in need.
Using our magic, craft a disguise as a regular human mortal, go out to the nearest human place, and I suppose just get to know how the common folk live. This lich has probably not had a normal interaction in hundreds or thousands of years. This might alleviate his boredom!
+1 to both, it's easier to sell stuff if you don't look like a lich.
Become a king. Conquest the lands. Every living either works for you or wins lifetime service in your undead army. Time to put all those magic skills and knowledge in use.
We already did that before and it was incredibly boring though.
Do it again, except do a religious takeover. That is, set yourself up as a god and supplant all the other religions.
Shapeshift into a human male and then conjure a typical "rich noble" suit, plated with golden foil.
If I succeed at shapeshifting, put the suit on and then conjure a pouch with 7000 gold coins in it. After that, search for some expensive restaurants in the nearest human place.
Why not just kill antagonistic gods before ascending? Godkilling is actually not that hard when you get down to it.
Alternatively, make an army of us clones, have them all ascend to demiliches, and glue it together into a hivemind demilich skeleton. This is a flawless plan.
Looking up the status of things on Deep Rot, it seems that the most recent articles are still at least a hundred years out of date, and those are largely vague. You will probably need to get the information yourself.
You consider your options and it seems there are two major paths you haven't tried to do before. You have the option of attempting to perform a religious takeover of society to ascend to a stable godhood through a large enough worshiper base, or you could perform an economic takeover of much of the world. You seem to recall that the current God of the Economy generally has a worse opinion among the gods than yourself due to pissing off the rest, so you could usurp him.
The thought of cloning yourself to help out with some actions comes to mind, but to do the best magic of that type, you need a few more resources that either of the paths could give.