D.R.Y.

Don't Repeat Yourself is a good thing to remember when you are writing.

When you are in the middle of a scene you may be tempted to describe events that have taken place earlier in the work. Don't.

Rookie writers repeat themselves because they fear the reader didn't get it, or they failed to completely cover the matter the first time and repeat themselves with a few more details later. The writer has a word processor that's perfectly capable of going back to the first point where it was mentioned so that s/he can rewrite it.

This can sneak into your work unawares. You may forget you said that already. Thus you may not catch this until you review your work as a whole. This is something you should be asking your beta-readers to be on the lookout for.

OR you may also be tempted to describe events that have taken place in other novels that you've written. That's another matter. Let's suppose the events that have taken place in other novels are things that would naturally come to the mind of the POV character at this point in the current narrative. It's natural to be reminded by similar  events or events with reasonable associations.

You do not want to rewrite the earlier novel here. That's stupid.

The reader of this work may have read the earlier work. If s/he enjoyed the work, a reminder of the pleasure of the earlier work is a Good Thing. If s/he has never read the earlier work, now's a good time to advertise.

Ah, that is another matter.

You want to tease the earlier work, but do so in a fashion that is natural from the POV character's perspective. When you are reminded of past events, it can be somewhat fragmentary. And that works to the writers' advantage. The POV character need not think of all the details. Maybe the event happened with other characters and what your POV character knows is incomplete.

Choose the most provocative aspect of the prior event and put that into your current narrative with only enough supporting detail to clearly convey it. Leave out just enough to pique the interest. Put in just enough that your reader will trust you have written an enjoyable prior novel. Be careful, there's a fine line between teasing and annoying.

You might add some new meaning that the POV character has gained through experience, or disclose something that you didn't get to the first time around. BUT tread lightly.

You can hide an Easter Egg, but that's all.