Abused Butia

[conrad]

I've a poor, sad, slightly malnourished Butia that I've been neglecting for muct too long now. It should probably have been repotted about five years ago but laziness on my part has meant that this has not happened.
Despite this it still grows away, if slowly, but the leaves are looking slightly yellowed.
When I find a suitable container within the next few weeks I'll do it a favour and will repot, in the mean time could I use a foliar spray of Epsom salts to help perk it up a bit? Would this work and what quantities should I use? If not are there any other recommendations for a foliar treat that will give it a bit of a boost?
Any advice on the proportions of compost/loam/grit/perlite/equivalent/slow release fertilizer etc etc to ensure that it's happy in its new pot?