You have put me in difficult situation by giving odd options to select as I am not sure what will be the out come of Janiper Block and Nargis Block in future. I can see some potential in Juniper Block and this potential is more better if the plots are on boundary but I am not sure about any future plans of Bahria Town. This potetial is that Lahore Ring Road will be passing after Janiper Block and its link may be given to Independence Drive of Sector C on Janiper Block. Besides this Overseas Enclave B is situated after Janiper Block and Bahria Town is trying its best to reach Lahore Canal from Janiper Block. Main Mosque and Community Centre of Bahria Town Lahore and Sector C Main School are also situated in Janiper Block. I am not sure when all these aspects will provide improvements to Janiper Block. At present Janiper Block is NOT fully developed and specially boundary plots are still not on ground plots.
If we see Nargis Block then it does not have any positive aspect in it other than being a part of Bahria Town Lahore. A Ganda Nala passes through Nargis Block and it is surrounded by villages. Until now its a dead end of Bahria Town Lahore. Nargis block is NOT yet fully developed.
The third option is also not a good one. Getting refund (though I am not sure that you will be getting full refund without deductions) after one year is also equally problematic.
If I am on your place then I will decide to keep Gulbahar plot and take Janiper plot even if it is on boundary (instead of boundary plot of Nargis Block) but it is important to get an existing (on ground) plot with possession (if possible).
With best regards,