Tuesday's programme was listed as Series 4, Episode 5, and marked as 5/16 (which suggests that there are 16 episodes in that series)
http://www.radiotimes.com/episode/dssj4y/first-dates--series-4-episode-5
The Channel 4 website says that Series 4 officially had 15 episodes in it but it looks like the unnumbered episode, 'The Proposal', would have completed the run of 16:
http://www.channel4.com/programmes/first-dates/episode-guide
So there are 11 more episodes in that series (and another two series after that) but it looks like Channel 4 has no immediate plans to show any of them, as (with the exception of two late-night repeats of the programme that you've just seen), there are no further showings listed.