Continue cubing my crushed skull?

Right now it's 138 atk with 1 enhance and unhammered.

It's unique, 3 lines. Line 1 is ignore 30% def and line 2 is 6% str.

It also has a 15% ignore def neb.

Should I continue cubing it, or should I just try and get a better weapon?

Better weapons might be harder to come by with the change to GM scrolls, so it depends on how much money you have to spend.
However, I'd recube since in my opinion, 30% PDR isn't all too useful given all of the PDR sources that we have these days(codex, nebulites, skill). Id go for boss damage+another useful line if you boss, or just two lines of % att or % total damage otherwise.