Redirecting after dynamic ip change on ethernet shield

I am using Arduino Due with Ethernet shield. I have a webserver setup with html files being served from SD card.

What I am doing:
I have a form on one of the html pages that lets user change ip, gateway, subnet, etc. I have this working. no issues here.

My problem:
When the user submits a change, I want to do the following things.
Step 1. Redirect to another html page, confirming the server is resetting.
Step 2. Reset the board.

On most html pages, there are css, js files which will be requested by the browser from the same host as the browser not yet knows the network settings has changed. How should I wait until all files to this redirected page has been served, and then reset the server?

On most html pages, there are css, js files which will be requested by the browser from the same host as the browser not yet knows the network settings has changed. How should I wait until all files to this redirected page has been served, and then reset the server?

Use a millis type delay while still checking the server for clients.