The plant itself needs no more K than other plants, but the term 'extra' invites questions as to its meaning.

Because N is the element used by plants in the greatest volume, generally everything else we supply by fertilizing is measured as a fraction of (compared to the amount of) N. Plants use about 2/3 as much K as N, so if you are using a high-N fertilizer and supplying fertilizer according to the plants N needs only, the plant will be receiving insufficient K. E.g., 30-10-10 is a 3:1:1 ratio fertilizer. Based on 3 parts of N, the plant would use 2 parts of K, but you supply only 1 part with a 3:1:1 ratio fertilizer. If, however, you are using a 1:1:1 ratio fertilizer, like 20-20-20, based on 1 part of N, you would only need 2/3 of a part of K (but you be supplying 1 part - more than the plant can use relative to N), so 1:1:1 ratio fertilizers supply 1/3 more K than a plant will use, so it's very unlikely that K would need additional supplementation with 1:1:1 fertilizers like 20-20-20 because you are already over-supplying relative to N.

The best fertilizer choice for her plant will have a 3:1:2 ratio. 24-8-16, 12-4-8, and 9-3-6 are all examples of 3:1:2 ratio fertilizers. I would give the nod to Dyna-Gro's Foliage-Pro 9-3-6 because, unlike most soluble fertilizers, it also contains Ca and Mg, plus it has all the nutrients essential to plant growth in the proper ratios. It hardly gets any better than that.

While there are several cultural conditions that can inhibit blooming, inadequate nutrition among them, the first thing I would suspect is tight roots - how long since it's been repotted? ever been root-pruned? and HAS she been fertilizing - with what?

Al