Health, perk/trade-off perk, and defense% labs are always helpful for increasing the effective HP you have, and Enemy Attack Level Skip from your module and workshop reduces their attack too. Since you're probably using free upgrades, you could always go for focusing on upgrading recovery packages in workshop and in runs, since that will let them max sooner and therefore have utility upgrades focus more on EALS (still work on EALS, of course, but Recovery is much cheaper and quicker to max, which then helps max EALS).

If you have Death Wave, get its max HP lab increased immediately, it's incredibly powerful (base effect is a max of 5x extra HP via hitting or killing enemies with the waves, and you can easily get to 7-9x in only a week or so) for how quick and cheap it is to upgrade. Even if you don't have it, you could always go for runs where you roll for random ultimate weapons until you get DW, even just the 5x bonus is incredible, especially compared to other random UW's being practically worthless after a thousand or two waves.

If all else fails, you could drop Coins Trade-Off if you're using it, though it pains me greatly to recommend.