they are making new manga episodes and are also planning to end the anime were the manga will end soo...
13th Hunter Chairman Election arc episode 137 it begins and then Dark Continent Expedition arc done
OT: Probably a small hiatus and they'll pick it up eventually. I don't how well the HxH anime is doing in a business standpoint but if it's good then they'll go on hiatus and pick it back up whenever the manga is far away from where the anime ended off. I doubt they'll do fillers cause I'm sure they want a reputation of "no filler" anime so I don't see why'd they'll do that.