There's been a few of this specific question popping up a few times in the past few months. You can look them up in the search bar in the event that my replies are not specific or sufficient for you.

I’m currently studying in a university in singapore but I want to reapply for medicine next year.

Did you previously apply? If yes, were you shortlisted for interview? Your initial A level grades will still play a role in determining if you get to transfer + your year 1 grades. Chances are extremely low. I've heard students transferring in YLL from another uni/course, but not in LKC. Number wise I'm not sure but really really rare.

However, in lieu of COVID, YLL did open up quite a few slot for overseas student studying medicine to transfer back to SG this year, as a M2.

I am trying to engage in more job shadowing experiences

With whatever is going on now, almost impossible to get a shadowing in public hospital.