At the moment unless you take a specific joker solo play in this game is very punishing, especially on higher difficulties as if you make a single mistake/get unlucky you instantly go down and that's it, your entire run is over meaning you're more likely to play it safe/passively. So I think it would be nice if when playing solo and you go down there is a way to get back up, whether that be via Roach or some other way, with it functioning in one of these ways:
You get respawns/revives depending upon difficulty - 3 for easy/normal, 2 for hard and very hard, 1 for nightmare (or maybe 2 for hard, 1 for very hard and 0 for nightmare)
or
You can get more respawns via upgrades (maybe part of upgrades to roach that I've seen is a popular suggestion) with the respawns increase either being a permanent upgrade (start with 1 for free, and can buy up to 3 or 5 with souls?) or be one that you have to refill/restock after you use one up (with the cap being 3/5 and also being bought via souls?).