I read a tip somewhere that really intrugued me to try it.
Apperently you can turn the tip of a felt liner the other way around when it starts drying out and you get a new nib. Naturally I couldn't quite believe this so I tried it on both my felt liners. One is a cheap one from Superdrug's MUA collection and the other is from Eyeko London which is about £12.99 but I got it in a magazine.
Please be warned that this can be messy so you will need some kitchen roll or lint free Cotten pads to grip the tip. The black can stain as it is still in my make up towel.