I just got done with my restaurant book not too long ago and might tell more people about it but this is one of the topics I talked about...here is how you deal with repeat customers:
First, you can obviously show them new stuff but eventually you will run out of material to show them. Do not try to perfect new tricks every week just for repeat customers.
You don't want to have different "sets" for new customers because they will come in at a faster pace than you can master new tricks so you want to spread your tricks out. Do your normal set of tricks and when you notice they have seen you perform before, ask if they want to see something new. Show them one thing and thats all. Tell them next time you will show them something new.
The reason you don't want to show them a whole new "set" is because you will only get to perform for them 3 or 4 other times before you've finished showing them everything you've got. If you show them one trick at a time then it will last a lot longer. That is the first part...
You will still run out of tricks to show them and what do you do in this case?
Talk to them like they're you're close friends. You won't go up to a table of your friends and start showing them tons of tricks. You will go up to them and ask them what they've been up to, etc etc. You will simply have a conversation. This is what you want to lead up to and just build a relationship with the people rather than being "the guy who does tricks."
You will notice that repeat customers don't want you to show them something new every time. Each repeat customer is different. One group might want you to perform the same tricks for a new friend that hasn't seen you perform. Another group will want you to do something new. Another group will just be ok with chatting. And another group might not want to see you perform at all. Every repeat customer is different but once you run out of tricks...build a relationship with them but talking to them like you would friends.
That is the basics of working with regulars
Thanks for your ideas and your post Benji. I think some of these ideas are good. I hope your restaurant gigs continue to go well. What will be the title of your book?