From my limited understanding:
I think it's a tough question you asked because I'm not sure if you understand what "realizing Dzogchen" really means. Because if you really realize Dzogchen and stabilize the realization, you are enlightened. You are Buddha. Done.
If you're talking about "glimpsing" the Dzogchen, or seeing for a second...that happens to many fortunate individuals who meet realized Lamas. But theres a quote that even if you've seen the nature of your mind
and you know what it's like, you are Like a Child on the battlefield
--you know who the enemies are, but you are helpless before them. So you are still a beginner--the practices look just the same for you as everybody else.
May I know what is the practice after the realisation of Dzogchen? One does not transform completely into another person after awakening, because there are habits that are not so easy to abandon. And it is not easy to always maintain presence.
1. If you've really realized Dzogchen...like, stabilized the recognition as they say, you don't really practice anymore. You're done.
You can engage in practice or look like you're meditating or do retreats, but it's just display. In fact everything in your life is always just display, only now you recognize that 100% of the time.
2. If you've really realized dzogchen, you may have habits but you're not attached to them anymore. You'd be happy to go without a cigarette for the rest of your life, or chain-smoke until the second you die. You'd be happy waking up to a cup of coffee or a cup of hot urine. No difference. Everything is the mandala of pure perception.
3. And if you've really realized Dzogchen, there's no presence to maintain or lose.
take everything I said with a grain of salt.
I think the stories about great masters are the best reference for me.