There is currently a 70,000 Chase Ink Plus sign-up bonus (there is no online link) going on right now. It appears to be a public offer that is available in your local branch, however if you have recently applied for the card and got in on the 60,000 sign-up bonus, you can send a Secure Message to Chase to ask to be matched to the higher bonus.
This bonus is spend $5,000 within 90 days to earn the 70,000 sign-up bonus. Typically, Chase will match to the higher bonus if you’ve applied within the past 90 days.
How To Get Matched:
1. Login to your Chase account
2. Choose Secure Message Center which is on the upper right hand part of the screen
3. From there, choose the Credit Card, you are inquiring about and write a short message saying you would like to be matched to the 70,000 point offer
4. From there, send your message and wait for Chase to get back to you and hopefully you’ll get matched!
You can also check out this Flyertalk thread on this matter which is another resource.
Have you sent a message to Chase, trying to up the sign-up bonus? What was your outcome?