Perhaps you need to find a new direction - losing interest in what you are writing about could mean that you need to find something that you can't not write about. Something where you don't have to force yourself and the words come faster than you can type them. Everyone has something that they could talk for hours about and writing about it should feel the same - less like work and more like telling a friend. By starting again and choosing something that comes more easily you can take everything you learned before and come back faster and stronger. There is no use keeping yourself roadblocked - I would say four months with very little productivity is a sign to start fresh.