Rotating between Victoza and Byetta

I just started Byetta today after being on Victoza for 1 year. It seemed like Victoza wasn't working anymore so I am cycling off for about 6 months. Anyone else doing this?

I'm not doing that (switching to Byetta) and am still on Victoza. But I'm curious: what do you mean that it seems "Victoza isn't working anymore"?