English term (edited): until we meet again

I'm assuming, apparently with justice, that you are seeking a Latin translation of English 'Until we meet again'. 'Dum inter nos denuo conveniamus' (lit., 'until we come together amongst ourselves again') is one way, perhaps the commonest and simplest, of rendering this idea. Others include: 'Dum inter nos denuo congrediamur' and 'dum denuo coeamus', both being merely synonymous ways of saying 'inter nos denuo conveniamus'.

The verbs in these sentences, introduced by 'dum' ('until'), are subjunctive, indicating anticipation or intent. When the notions of intent or anticipation are absent and the emphasis is on the actual occurrence of the event, one usually employs 'donec' or 'quoad', rarely 'dum', (all = 'until') with a verb in the indicative, usually in the perfect tense.

Thus, if your expectation of encountering your friend again is such that it amounts to certainty, you should employ 'donec' or 'quoad' with the perfect indicative of one of the verbs which I've mentioned, the commonest and simplest way of expressing this being, 'donec [or 'quoad'] inter nos denuo convenimus'.

N.B. I do not recommend substituting 'iterum' for 'denuo', since, although both mean 'again', the former is restricted to 'again' in the sense of 'a second time', while 'denuo' may be used of any number of encounters.