We present observations using the Baade Magellan and Canada-France-Hawaii telescopes showing that main-belt comet 324P/La Sagra , formerly known as P/2010 R2 , has become active again for the first time since originally observed to be active in 2010-2011 .
The object appears point-source-like in March and April 2015 as it approached perihelion ( true anomaly of \nu \sim 300 ^ { \circ } ) , but was \sim 1 mag brighter than expected if inactive , suggesting the presence of unresolved dust emission .
Activity was confirmed by observations of a cometary dust tail in May and June 2015 .
We find an apparent net dust production rate of { \dot { M } _ { d } } \lesssim 0.1 kg s ^ { -1 } during these observations .
324P is now the fourth main-belt comet confirmed to be recurrently active , a strong indication that its activity is driven by sublimation .
It now has the largest confirmed active range of all likely main-belt comets , and also the most distant confirmed inbound activation point at R \sim 2.8 AU .
Further observations during the current active period will allow direct comparisons of activity strength with 324P ’ s 2010 activity .