Some rather useful research, via Tom Baker:
Working with Engaging Networks, PETA France demonstrated that advocacy is an effective way to engage lapsed donors. They sent out various emails on the issue of seal clubbing to a total of 22,000 supporters.
As well as finding a correlation between level of activism and response rate, the more active the campaigner, the better the response rate. They also found that lapsed donors were significantly more likely to donate if asked to take action first then donate.
That’s a tactic also applicable to re-recruiting lapsed members, which should be an important part of any membership strategy.