When I use this ability, does the Icebreaker keep the extra strength forever? That's the way i've been playing it, since there are other cards that specify that the extra strength for them is limited to one run or so. Just wanted to make sure and get your input. Thanks!
From page 16 of the rulebook:
Many icebreakers allow the Runner to temporarily increase the icebreaker’s strength by spending credits. (…) This strength increase lasts only while the current piece of ice is being encountered, unless otherwise noted by card abilities. After an encounter with a piece of ice, the icebreaker’s strength returns to the value shown on its card.
So the strength increase only lasts for that encounter with that particular ice. The ones that keep the strength boost through the whole run are actually at an advantage.