What evidence should I retain?
Preserve relevant specifications, samples, code, release notes, and communications explaining the change. Compare each version with the claim language in its patent context. Section 271 concerns the acts accused of infringement; a later redesign does not itself decide whether an earlier version infringed.
Can contentions simply be updated?
Check the governing rules and order. As one example, Northern District of California Patent Local Rule 3-6 requires a timely showing of good cause for amending infringement or invalidity contentions. Rule 16(b)(4) separately governs modification of a scheduling order. Discovery of a change is a reason to assess amendment promptly, not permission to ignore those requirements.
Does redesign eliminate willfulness risk?
No categorical conclusion follows from the change alone. Halo v. Pulse Electronics directs attention to the circumstances and culpability at the time of conduct. Evaluate the evidence and timing rather than describing every redesign as either an admission or a complete defense.