Welcome to Nico!
Check out these two posts. They're chock full of everything lift-related for our vehicles:
suspension-lifts-101-t491011.html
the-final-word-on-lifting-the-r50-at-a- ... 85532.html
From what I've heard, longer shocks aren't generally required for lifts up to 2", especially in the rear. The only time they'll come in handy is when you're going over bumps quickly and they end up topping out, but even this isn't necessarily a problem for the shocks as much as a "don't want to hear that noise" issue. It usually only happens while the springs are getting settled during the first months.
That all being said, fleurys' lift system (2nd link) also completely sidesteps this topping out issue in the front by extending the entire strut, not just the spring. The rear also shouldn't suffer top-out in the rear as bad either since you don't need to use stiffer springs.
Are you being proactive or are they already topping out on you?