Googling for how to refill my Faber-Castell PITT pen, I found a good tip on The Web Comic List (Anyone using Faber Castell PITT pens?). It is this YouTube video about how to use the other end of the nib to get a whole new fresh (and sharp) tip.
And how about refilling your marker? well, look at the back. There is a cap you can remove with a pair of pliers (gently). Once you have, you can refill it with India ink.
Don’t put too much in there, because it will overload the felt and drip from the nib. If that happens, keep your pen vertical, let it drip for a minute and use a piece of tissue paper to remove the excess ink. Always do this over a piece of disposable paper, so your furniture doesn’t get stained permanently.
Once you’re done, pop back the cap, and start drawing.
By the way, I tried the resharpen trick on my Faber-Castell PITT artist pen big brush, and I saw it didn’t have a double tip. The other side of the nib was blunt. Ah well, you can’t have everything.
That is all.