Wellbutrin not working anymore?

Hey everyone! I’ve been on Wellbutrin for about 5 years and it’s been great. It really helped with motivation and negating the negative side effects of Lexapro. Lately though it feels as though it isn’t as effective. The negative effects of Lexapro are becoming more pronounced and I can’t get myself to do crap. I experienced this before so my doctor would up the dose, but now I’m at 450mg. Me and my new doctor are really hesitant to up the dose. Has anyone experienced this before? Does anyone have some tips to help with this?