I know two couples who did that.

The first couple got remarried for a stupid reason, and wound up divorced a second time. They never bothered to work out the problems that caused them to divorce in the first place, so they still had the same problems.

The second couple was divorced for quite a few years. They each spent time working on themselves - getting their careers going well, getting their finances in order, and basically becoming whole people. They ran into each other at an event for a mutual interest and began chatting. This led to dinner just to “catch up”. They did this a few times, very casually; and then began dating. After a couple years, they got remarried and have been living happily ever after for nearly 20 years.