From the parking at Le Laus follow the road south (towards the Col d’Izoard) until it is blocked off. On the left there should be a ski de fond track which you follow into the valley on the left (south-east). From the hut after a long straight section it bears left and climbs steadily. At around 2052m you should find a small bridge on the right of the track. Take it and then work your way south- west through the trees. As the trees thin out you will see L’Arpelin east face on your right. Continue going south into a small bowl. As the ground starts to rise towards the Cote Belle turn right (west) and make your way to the Col Perdu. From here head north up the south face of l’Arpelin to the summit.
Just to the east of the summit a short steep section leads onto the north face. Descend wherever the snow is best until you reach the trees, then start to bear left (west) until you pick up another ski de fond track which leads down to Le Laus and the parking.
Option 2:You can always ski off the summit as above but as the ground gets less steep, turn east and travers round to the east face, ski this and then rejoin the way you came in. Grade 3.2 - East facing