Any advice for this plant?

Hello! I was given this plant a year ago by a friend who was leaving the country. It used to be covered in leaves but they've all fallen off (last picture shows what it looked like when I got it). It's still alive but I don't think it's healthy. Is there any way to restore it to its former glory? Should I repot it? I'm not sure what it is either (doesn't look like Kalanchoe as it says on the pot). It rests in sight of a window too. I used to water it once a week but I've reduced that to once a month. Many thanks!