If you want to indicate that you are about to summarize briefly something that you already said, for clarity rather than for emphasis, you can use the word recapitulate, which means
to repeat the main points of an explanation or description
In an informal situation like a group chat, you can abbreviate it to recap. For example, if you wanted to summarize the plan for the weekend that you have just discussed, you might say
Just to recap, we'll meet at the restaurant at 6 on Saturday, then go to the film afterwards, and we'll meet again on Sunday morning to go for a walk, followed by lunch at a pub.