Is it possible to replace the female u.fl connector on the cable side of antennas or is a specialized tool needed for this. I was very clumsy and managed to chop off the ufl connectors on two perfectly good antennas. These female connectors seem very hard to find, unlike the male smd plugs. Has anyone tried replacing these u.fl plugs on the cable-side or know a source for them?

Yes possible. Plenty of video on YT.

I use a set of Engineer PA09 crimping pliers for those (partially). But you can do it by hand with needle nose pliers, tweezers and good eyesight.

Ok, so the center wire just slips into the connector, not even soldered? I guess I has some old rx antennas I can try and salvage a connector from.

It's not soldered just crimped. You could buy some ready crimped wires and solder the other end. (they are cheap) Would be an easier task than trying to recrimp these connectors.