How to get servers to re-federate/re-subscribe after a time offline?

Hey all,

My personal home-hosted server ran out of disk space and so went offline while I was away and I didn't notice it for a week or two.

This meant that federation requests (or subscriptions requests) went offline and now most of the servers I'm federated with are lagging. I'm only getting updates from a couple.

Is there a way to trigger federated servers back to life so I get the subscription updates? Federation does seem to be working, given some servers seem to federate fine and this post was via federation and has worked.