Palm fonds going brown

I have a palm tree with the tips of the leaves going brown. I re-potted it about 3 months ago into a slightly larger pot and filled it with my usual palm mix of general compost and sand 50/50. This has always been ok with my other palms and they are thriving. I also feed it with palm fertilizer, once every couple of weeks and only use rain water. The centre of the fronds are all green and generally it is healthy but I feel it is a fine line between living and dying. Any help or advice is much appreciated.