(Go Team Metal removal).
If the problem is refleeting time, then one solution would be to faux speed up time (training montage!). That sounds ridiculous, but it is possible. Just increase the rate of resource income, build speed, and AI fleet growth (and aggression).
In a system where Metal is used for Ship Caps (i.e., the metal less economy), it's easy because there is no resource income, you just speed up build speed (and also get attacked by 30 minutes of accelerated AI ship growth). It becomes a 'faster' game, where after every attack you make against a planet, the AI will counter attack more vigorously. You can conceptualize this as momentum changes or taking turns (ala the Chess analogy). (Caveat: This will have repercussions on fleet experience.)
In the current Metal Economy, it's harder. An example of this already are those structures that give you 100K metal (or whatever) for destroying them for 1 AIP. That's a terrible trade for me. And having an acceleration that costs AIP is likewise not appealing. If I can spend game time for AIPless recovery, then I'll do it (because I'm a terrible person). So then you are stuck increasing build speed and AI fleet growth (which are easy) and metal income rate increases. That last one... is hard, because that means you now have an off/on state to control fake game speed.
But maybe I'm overthinking it? Maybe there should be a "rebuild mode" button that applies an acceleration parameter on those three rates. Then after an attack, you enter rebuild mode, deal with the incoming attacks, and then you are ready to go again. It's really similar to how hacking works.