Container fig tree has no leaves

I was "given" a container fig tree for Christmas, but it has lived at my parents' ever since. I have only seen it in person about three times, but get sent occasional photo updates. Last year, it had loads of leaves by the middle of June, but none at all this year. There are nice green looking leaf buds at the end of the branches and a few figs forming, so it looks to be alive but very behind where it was this time last year. Looking back at photos, the leaves were just starting to come in by the middle of May last year and it was looking nice and leafy by mid June.

My Mum assures me it has been watered through the dry period (including with some diluted vermijuice), so she is a bit puzzled as to why there are no leaves. It probably could do with being potted-on but for now, I've suggested she try mulching it with some good compost as that has perked up my poor pot-bound rhubarb. I suppose I could also suggest she remove all the fruit so it puts all its energy into leaf growth? What about giving it a nitrogen feed? All ideas welcomed!