I'm afraid not. Normally we can save the config file as a backup. But the config file of WDR4300 will cause some problem if you upload it after upgrade, which has been reported by many users on this forum.
http://forum.tp-link.com/showthread.php?79755-Config-files-unusable-after-firmware-upgrade

Thanks for this reply. Most disappointing. I guess I'll just have to get another router. I was intending to update because my TL-WDR4300 goes to sleep every 2-3 days and has to be restarted to wake it up. I was wondering whether /hoping that a firmware update might eliminate the problem.

You keep the router on all the time except that it goes to sleep after 2-3 days and you'll restart it? When I don't need to access internet during night, I'll power off the router and let it have a rest.
When it goes to sleep, can you login web interface of WDR4300?
Not sure that the firmware will fix the problem or not if you don't try it.

Thanks for the reply. Unfortunately I can't shut it down at night because "night" varies according to where I am. I'm now beginning to wonder whether the router is giving up the ghost because my NAS admin service has emailed me several times over the last few hours to say that the NAS has become disconnected from the rest of the world and then mailed 30-40 minutes later in each case to say that it had reconnected. You are, of course, right with your "Not sure that the firmware will fix the problem or not if you don't try it" but I cannot afford the time to copy all the settings by hand and then reprogram them.
Re. the "When it goes to sleep, can you login web interface of WDR4300?" the answer is "Yes".