Should I upgrade my camera or lenses?

[iluvphoto]

I want to upgrade my lenses. I don't have a big fancy camera and I plan on upgrading that around September. Would it be better to upgrade my camera before I do my lenses or the other way around?

Right now I have a Canon EOS Rebel XSi. I want to upgrade to a Canon 7D.

My lenses right now are an EF-S 18-55 f/3.5-5.6 OS, EFS 55-250 f/4-5.6 IS and a 70-300 f/4-5.6 Macro.

I do landscape, nature and food photography. What would the best mid-priced lenses be for these?

Thanks!

[i speak in math]

What will upgrading to a better lens, or better body, let you do that your current lenses or body can't do now? In other words, what is holding you back?

[andsome]

Surely it has to be personal choice. No one can advise on this without knowing your personal circumstances. Only you know what you want to achieve and what you can afford. People on here can only give a personal opinion if you ask for opinions on a choice of several products within your price range.