Ok so what you want to do with Neobux extending is look at how long it will take you to extend your 72 RR's under 100.
You seem to be doing around 10 a day so that = 7 days.
If you have RR's between 100 - 107 days now they will go under 100.
You need to make sure you don't get stuck in a constant extending by 15 days cycle.
Sometimes ext by 30 days is better as it gives you a lot more time.
15 days ext is the most expensive.
You can also look at autopay in this situation - do you know how that works?
Basically it can slow down the system because it pays to hold RR's in place for 1 day and so less RR's will fall under 100 days.
Hope that helps - maybe you have thought about it already but just wanted to check
What I like to do is monitor the numbers and work on targets - for example I have 16 over 100 days now and am aiming for 20, then 30, then 40. This helps me make sure I am moving forward in my plan.....