Is there ever a point in negotiating if you're not willing to walk away?

Here's my situation: I work as a freelance musician, and there's one bar that I've been playing at regularly for a year. The fee is a bit low, costs around me are going up, I know that the bar manager trusts in my abilities to bring a good vibe at the weekends, and the regulars like me, so I'd like to raise the fee. The dates when I play there are booked month by month individually.

But - if I communicate a 15% or 20% increase to my fee and the manager rejects it, I don't think I'd actually be willing to lose the gig. It's been a steady source of work for me and I like the stability of having it without the overhead of always having to find new venues. I'm not too confident that I could quickly find another venue to fill its place in my schedule if I were to stop playing there.

What would you do in my situation?