When we retry after deadlocks, we are very likely to overwrite other processes' changes. We need to be aware that very likely someone else modified the data we intended to modify. Especially if all the readers run under snapshot isolation, then readers cannot be involved in deadlocks, which means that all the parties involved in a deadlock are writers, modified or attempted to modify the same data. If we just catch the exception and automatically retry, we can overwrite someone else's changes.
This is called lost updates, and this is usually wrong. Typically the right thing to do after a deadlock is to retry on a much higher level - re-select the data and decide whether to save in the same way the original decision to save was made.
For example, if a user pushed a Save button and the saving transaction was chosen as a deadlock victim, it might be a good idea to re-display the data on the screen as of after the deadlock.