Advice on backup routes

I've tried to look this up, but I could use some clarification.

I'm working on some backup connections for my sites. What it looks like now is MPLS primary and a VPN over internet as backup. I'm redistributing the routes via EIGRP from the MPLS and they're coming in with an administrative distance of 170.

My assumption was that I could set up a static route for my VPN with an AD of 180 and that would take care of that. However, what I'm seeing is that it works well when the mpls goes down, but when it comes back up my router won't give up on that static route with the higher AD.

Would someone be able to tell me why this acts this way and if there's a better way to do it?

Also: My routing gear is Cisco but my firewalls which host the VPNs are not. Is going to OSPF across the board the ultimate answer to this?