Why didn't the Cêpans make a plan to get back together after training the Loric children? They were on the rocket heading to Earth. There would have been time then to formulate a plan of reconnecting.
I think they had a plan but couldn't execute it because they all died - like Thomas in his comment has pointed out. Remember the white tablet which can track every living Garde remaining (and their ship) that Pittacus gave Malcom, that Henri said he would come back later to retrieve when needed?
- In Henri's letter for John (Four)
The last thing I have to tell you is that we didn’t move to Paradise by chance. Your Legacies were delayed and I had begun to worry, and when my worry grew to a full-out panic when the third scar appeared—knowing you are next—I decided to seek out the one man who might hold the key to finding the others.
- The Power of Six, Chapter 18
- In the conversation between Malcom and Lexa (Aka GUARD later)
"... Pittacus told me to keep this tablet safe for the Garde, and that’s what I’m going to do. One of the Cêpan—I believe his Loric name is Brandon—said he’d be back for it if there was trouble, or when his charge was at the age when he would start developing powers or whatever you know them as.”
- The Guard, Chapter 3