My current client have requested a full campaign, brochures, website, all material except they have requested that the logo stays the same. They are a relatively mid-sized company, and have had the same logo since 1994. I'm trying to persuade the founder and owner the positives of having a complete design but he's older and has a lot of sentiment to the logo as he designed it himself. I have on a number of occasions shown him competitors logos and branding, good and bad logos and he does have a good eye for picking out the higher quality designs, yet can't understand why he would need a new logo.
In a nutshell, what's the best/generally good approach to demonstrating a positive reason for a logo redesign. Since I'm designing the rest of his company I think it's suitable that the logo ties in with the rest, not the rest ties in with the logo.