I'm on week 5 of lexapro (escitalopram) 10mg. feeling improvement but still have anxiety. should i ask for an increase to 15 or 20mg or just wait until 8 weeks?

I'd wait it out: As a therapist, I often tell my clients that the meds aren't there to eliminate your anxiety; they're there to make it more manageable. For long-term, sustainable anxiety reduction you might consider learning some CBT, ACT, or mindfulness techniques. Check out a book called The Happiness Trap for some great strategies. Best of luck!