Meaning of "we mustn't leave it so long next time"

[Satke]

Business Idiom in English, Intermediate level

ESL/EFL Test #130 "Way of saying goodbye", question 8

It's been great meeting up again and we mustn't ......... it so long next time.

(a) leave
(b) take
(c) wait
(d) lose

Business Idiom in English, Intermediate level

ESL/EFL Test #130 "Way of saying goodbye", answer 8

It's been great meeting up again and we mustn't leave it so long next time.

Correct answer: (a) leave

Your answer was: incorrect
It's been great meeting up again and we mustn't take it so long next time.
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Can you please explain meaning of the last part?

Thanks
Satke

[Mister Micawber]

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We should meet sooner next time (not leave our next meeting until such a long time in the future).
.
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Native English teacher at Mister Micawber's