reinit NFS client without restart

I have been working on my server, from which I export one directory using NFS. Of course over the week or so of server reboots, I multiple times forgot to umount the export filesystem in my workstation (which gets mounted from /etc/fstab on boot). In between I was able to umount after the fact and remount (I am not using autofs):

umount -fl /data0
mount /data0

But this no longer works.

I cannot mount the exported directory from the server on a different directory (mount hangs), but I can nfs mount that exported dir on a virtual machine running on my workstation.

What I tried is removing (rmmod) the nfs and nfsv3 module (which would not work: Resource temporarily unavailable). lsof hangs. mount doesn't show anything mounted via nfs. This is all probably a result of using 'umount -l' multiple times, but the first two times this worked without a problem.

I have restarted the server in the mean time, after not being able to mount without that making any difference. I also used service nfs-kernel-server restart. I suspect everything would be back to normal if I restart the client workstation.

Is there a way to recover from this and reinitialise the nfs client side on my workstation without a reboot?

If I cannot fix this without reboot, would this not reoccur if I start using autofs?