It was closed for much of 2014, with a rumor that it wasn't going to re-open, but it did re-open as scheduled. As wdwfan22 said, I haven't heard anything about another extended closure for Nemo at this point. I think DLR is so focused on the 60th anniversary kick-off in May, that any planned major/long closure that is going to happen in 2015 has already started.