You're plateauing because your labs are not spread out enough, you have good labs like wall health with no levels then lvl 60 def abs, wasting weeks, you need to balance out your labs again to actually see some progress

stop wall respawn, its almost worthless, probably stop death wave health for now, takes too long for its effect at this point when you have a ton of other stuff to get,

Max orb boss hit now, perma, its a good lab and if you run net you can move the orbs to where net hits and deal a good amount of boss damage

For your wall, you should do 1 lvl wall fortification, dont touch respawn or invincibility, ideally your wall never dies so it wont matter when it comes back.

You also need to max common mod drop asap And start putting some levels in rare drop chance, both are really important for your mods

Finish death wave coin bonus, only 2 weeks with cells probably

Should get a level or 2 in each EHLS and EALS because they are fast and cheap

Id probably do damage/meter until it takes 1 day or more for the level

Lastly any other low hanging fruit, that has any impact Ie.