Let's catch up is a suggestion to meet and swap news. We must, let's catch up soon.
It means a conversation rather than an occasion, so a coffee is enough. Whether a date follows is the test of whether it was meant.
1phraselet's catch upA suggestion to meet and swap news.
“Let's catch up properly when the term is over.”
let's catch up is a phrase.
Practised in Small Talk & Everyday Phrases