Brohan,
I strongly recommend you change the valve. The valve can be changed quite easily with the right expertise (a few minutes of work, don't even need to remove the bladder from the LE). To remove it you will simply need to immerse the valve in boiling water and peel it off slowly. Then clean off all the glue with Meth spirits and then alcohol. Sticking the new valve back in is the tricky part of the job and you need the right setup for this...
Contact us through the our shop
actionsportswa.com.au/ we have these spare Core valves in stock. Just replaced one with Darren's help 2 days ago and a few others over the last 1.5 year, all still going strong.
If you don't feel comfortable doing the repair yourself you could probably mail your bladder in.
Christian