Here is a link to the service manual for your Ideapad.
On p.37 it shows how to remove the cable from the card (as you already know).
It is interesting that the WLAN antenna cables are not listed in the parts inventory in the manual.
Are the antenna connectors on the new WLAN card (is it the same model card?) the same as on the old card?
If the antenna cable connectors are solid (filled) and the old card antenna connectors are hollow then the cables are the male and the card is the female. If this the case, are the antenna connectors on the new card, female or male?
If they are male then you may have to improvise the connection by making new antenna cables with the appropriate connectors yourself. You will have to trace where they go to. Make sure that the new cables, if you make them, are exactly the same length as the old to ensure that are 'tuned' to the correct frequency. Alternatively you could just solder the connections, (be quick, use a hot iron so that you spend the minimum amount of time applying the heat to melt the solder).
So the new WLAN card connector has an inner pin, separated from an outer sleeve, is this correct? So it is expecting a two wire (or wire and shield) connection.
If the new WLAN card is a different make and model to the old card, have you verified that the new WLAN card is compatible with your laptop. Just because it slots in OK doesn't mean that it will work, regardless of the antenna connection..
What type of connector does the old WLAN card have? If it has no pin in the middle and only an outer sleeve connection then it is expecting only a 1 wire connection, which will be shielded in a different manner.
As a test try just temporarily connecting the pin of the card connector to the cable connector and see if it works. Do not let it touch the outer sleeve connection of the connector on the card.