When praying for someone long-term, such as a family member, get into the habit of praying for small victories in the form of today's spiritual influence on them. This will prevent vain repetition, as well as get specific and will help you develop eyes to see the answers to these small victories.
This was recently written by Josh Etter on the Desiring God blog here.
When I first read it I thought this suggestion was REALLY helpful. I find praying for people/issues over the long term difficult. I don't think it's a matter of not trusting God to answer those prayers. It's just plain hard work, it becomes tedious at times and then it drops into the realm of the autopilot. This advice breathes new life into long haul prayers.
Then as I reflected on the advice I began to wonder whether it was a case of modern management practices taking over the things of faith once again. You know...set a goal, break it down into its component parts, tackle it one small step at a time until the goal has been reached. This is a helpful model in so many settings. But is it relevant here - when praying for the big issues over a long period of time...for someone's salvation or for their ongoing health and wellbeing, for the life of one's church or for ongoing gospel opportunities within our communities?
And then I remembered...
Give us today our daily bread.
Therefore do not worry about tomorrow, for tomorrow will worry about itself. Each day has enough trouble of its own.
As a Christian I am exhorted to live one day at a time under God. Yes, I need to keep my eyes fixed on the end of the race. But for today I only need grace for today. And yes, I need to keep my unsaved friend or relative's long term need for a saving knowledge of Jesus in my prayers but they too need specific grace to see God at work in their lives in a way that is specific to today.
So yes, I am very encouraged by this suggestion. And the added benefit of cultivating gratitude can only help to keep us spurred on in the hard but good work of praying over the long haul.