I am afraid that there is no 'quick fix' for cloze.
I've found that ultimately a well read child who has read a rich variety of good quality books and non-fiction material, will do well with cloze - far better than a child who has spent two years practising paper after paper but has not been reading.
As well as reading, vocabulary and general English knowledge is built through family conversation, and listening to good quality programs on the radio and TV, and listening to audio books.
I must admit that my ds2 was a bit of an exception. The stubborn boy has never read much fiction - but does read non fiction science/technology magazines.
Yet he was surprisingly good at cloze and I believe this is because he is hearing-impaired. As he was used to only ever hearing about 70% at most of a conversation, and 'filling in the blanks' in his mind, cloze may have come more naturally to him.
If a child can hear well, I am afraid they need to start reading