Is there a way to configure RabbitMq to not close connections after missed heartbeats at all?
No, but you can disable heartbeats

eandersson is right, no you can't do that. but disabling heartbeats is probably the wrong idea, too.
the point of a heartbeat is to tell you when your connection to the server drops, so you can take action as soon as possible.
common actions include (but are not limited to):

crash the app and restart, recreating the needed connection(s)
re-create the connection(s) without restarting

how you handle the missed heartbear / dropped connection is up to you, but ultimately, the missed heartbeat is a sign that your connection is already dropped, not a cause of dropped connections.
Is there a way to configure RabbitMq to not close connections after missed heartbeats?