I've been birding for about 20 years, and there are always new ways of getting "lifers". For me, getting real lifers nearly always now means going on a twitch looking for a rarity seen by someone else - especially in my own Province (Nova Scotia), as I've seen most of the birds that can easily be seen here. The Provincial list is to me more important than my life list, as the latter depends on how much (or little) time and money, and family and work committments I have to travel to bird.
However, now that I've been into digiscoping for the last year or so, I have started a new life list - Birds I Have Successfully Digitally photographed - definition being a sharp, decent shot, that identifies the bird and looks reasonably technically competent. It's given me a whole new lease of birding life. Also, in the last few years I have been able to travel to more exotic places, and birding there (e.g. Central America) is like being a beginner all over again - great rejuvenation!