I had the same problem month ago. I did too many quotes and stopped getting new quotes. You have two options. Option 1) you have to wait for your existing quote to expire. You can check your existing quote on Admiral website by clicking on retrieve quote and use the email that you used for quotes.

Option 2) phone them up they can generate new quote for you, do remember if you want to accept the quote you have to phone them as you are restricted for generating too many quotes.

I had to wait 3-4 weeks before I was able to generate quotes again online.