ranjit I think this takes a lot of self-discipline (that I'm not sure I have). That's why it tends to work better with actual other people involved.
You're already using a metronome, which is good... How about committing to making a recording it and posting it afterward? That won't be the same as MRC's suggestion of actually playing with someone, but it does engage the "other people," at least a little bit.
The only other thing I might suggest is to revisit the "advice" about sightreading to see if there's anything you either are not doing (but should be) or are doing but could be doing better.
For example, I am really bad about reading bottom-up, i.e., from the bass clef up. I tend to read from the treble clef down.
Also, how far are you looking ahead? Is it enough? Not too much/too far?
How much info are you getting from the score before you start playing? Is there anything there that you can tweak?
Also, by that token, is there anything you can do (or do better) when you're away from the keyboard?
I assume you know all of these things, but it's often helpful to revisit things and see if you can do any tweaking or fine-tuning.