In my experience, unless you're living with all of your friends in the second year, the social side goes from being a group kind of thing to more of a dispersed network, with lots of different groups and individuals all over the place, many of whom aren't friends with each other.
The workload is larger, but more interesting. And - because it counts - you're taking it more seriously. Putting more time into it.
If you overdo it, this can end up with you going a little bit mad, eating too many ready meals, not leaving the house enough, and forgetting what socks look like, particularly around deadlines.
So, what you need to do is balance your working hard with playing hard. Clubbing isn't as much fun, as you'll have seen it all before, so it's better to entrench yourself in the pubs and bars, cook for your mates, hit a few house parties, bumble around town aimlessly, and - if you're into it - focus on some of the sport / societies stuff.
Being responsible for a house is a bit weird, particularly when it comes to bills, tidying up, shifting furniture, sorting out internet connections, and so forth. Make sure you get on with your housemates.