Here are few suggestions, which you can bring together or one-by-one.
SUGGESTION 1:
Bring awarding best team member of the sprint in your Retro:
- Ask the team to vote during Retro
- Collect vote in room by raising hands
- Use vote box to vote for best developer / tester of the Sprint
- Before Retro, run a survey to collect
- Instead of asking for a single rating from each team-member, go with ranking approach. Ask team to rank for everyone's choices as 1.2.3 and mark them with values 5, 3, 1 respectively. Use sum of values of all team members to determine The Developer of the Sprint.
SUGGESTION 2:
Things that were identified in previous Retros (whether practices or procedures), try to gauge their improvement paths - Identify maturity level on a scale of 5 and make team to discuss it.
- This helps to know what they discussed earlier (as a refresher), as well as if they are sticking to it.
SUGGESTION 3:
Identify wastes in the previous Sprint - This helps to understand why something is not necessary and make the Team to qualify it.
SUGGESTION 4:
Discuss Customer Satisfaction Index/Factor from previous deliverables.
SUGGESTION 5:
Bring innovation - Any change to an existing approach - Determine if there any new way of trying to do something, and implement them - Brainstorm.
SUGGESTION 6:
Every 3-4 Sprints, show a 5 minute demo of the product before the 3-4 Sprints' and show the current one. (Maybe record a video of the product every Sprint-end). This actually gives great motivation to the Team as, with the speed in which things are delivered, people get less time to look at the path traveled.