ranjit I really struggle to focus on practicing on pieces that are mostly learned, where you need to focus on evenness, small memory slips, consistency, and difficult sections. How should one deal with this
There is something else you need to focus on, more and more as you progress towards the moment where you might perform the piece: deepening and refining your interpretation. For me, this is what makes the last stages of working on a piece the most interesting. Working on all the things you mention - evenness, memory, consistency - stops being boring if it is done with the aim of finding a way to tell a more captivating, moving story.
Usually, the more I work on a piece, the more new expressive possibilities I find in it. Sometimes working on technique - playing slowly, playing a legato passage staccato, playing a forte passage pianissimo - can inspire some change in interpretation. Or the other way around: a change in phrasing can lead to a change in fingering.
If you feel the need to repeat a difficult passage a lot to make it cleaner or to get it memorised, don't grind through those repetitions mechanically: try all sorts of different ways of playing it. Play a rapid passage languidly, try all sorts of rubato in a passage that's usually in strict time, or take a passage that usually has a lot of rubato and use the metronome to force you to play it without all that freedom. Add accents in unusual places, use different phrasing, invert staccato and legato.... You can be as extreme as you like - nobody is judging you - but in the midst of all this messing around, you may actually find moments where you say to yourself "hey, it actually sounds better that way!". Or you may at least decide to keep a subtler version of some exaggerated idea you cooked up. If you're being creative, you shouldn't get bored!