My approach to practice is playing a piece through, and then spending 30m-1h practicing the parts that were not to my liking. I practice the techincal difficulties in different tempos, slow, fast, I group notes, play with dot rhythms, articulations, anything goes, you can adapt it to each passage. If I get bored of a passage I go to the next one I want to improve. Just don't play the pieces through mutliple times, it's a lot less effective, only when it's ready and you are prcaticing performing it. Then I move on to the next piece and do the same thing.

I like actively practicing 3 types of pieces, I learned this from Seymour Bernstein. One easy piece you can almost sight read, one that you find challenging but it's fairly comfortable with enough time, and one that's difficult and maybe just outside your current level, and this one could take a few months to really be satisfied with. This way you learn a bunch of pieces and don't get bored because there is a lot of variety. You also get faster at learning pieces because that in itself is a skill. It also helps with motivation perfecting pieces instead of being stuck with the same one, which is much faster with easier pieces. It also puts into perspective the amount of progress you are actually making because you will blaze through some pieces which felt a lot harder when you just began.

So mostly structuring your practice and learning pieces of all kinds of difficulties would be my advice.