This seems to be a pretty common problem -- I've inherited a couple of projects suffering from this, and I've been guilty of it plenty too.

When a project goes to maintenance, it really becomes a completely different project. The skills that launched the project aren't the skills that are needed to keep it alive forever.

There are people who really prefer doing maintenance. They hate looking at a blank page, but they're happy to chew through bug reports and feature requests and make small changes to code or design all day long. Try to hire one or two of those people (and, honestly, they rarely command the kind of pay rate that a creative team does).

Client's happy, team's happy, you get residual income.

...I might be talking out of my ass though, I haven't gotten to this step yet.