I'm having the same problems, LakeMIchigan. I finished my first draft of my book almost two years ago, and I've gone back and forth on it. Sometimes, I think it's salvageable with re-writing and sometimes I think I just have to move on.
As long as you are enjoying the writing process, I don't know that it's ever time to give up on writing itself.
Giving up on a particular project? Three years may be enough. How many times have you changed it up and re-written major parts of it? If it's more than twice, I'd say it's time for some mental housecleaning.
Try a new project. Set the old one aside and put it out of your mind. Start something fresh, with all your experience under your belt. Your writing will be better for it.
For me, I tried. Really. I have started two different books since I tried to put my first one away, but it was nagging at me. I set myself a concrete timeline, though. I will finish my final round of re-writes at the end of October, then I will not mess around with it again until and unless I have an agent or editor asking for changes. Starting Nov 1, I'm doing my own NaNo. Ten 5,000 word stories in the month of November. Time to use some short fiction to get my blood pumping again.
Edited by: MYREALANA at: 10/21/2014 (12:36)
--Myrea
"If you can't do something smart, do something right." --
Shepherd Book