Upgrading my game package on Steam

[Kek]

How would I go about upgrading my game package if I already have the game on Steam?

 

[The G-Meister]

Just message one of the Devs! See that little "Inbox" button next your your alerts? You can send a new private message from there.

 

[GarlicJelly]

I just copy/pasted this from another thread:
I don't think you can upgrade your purchase in Steam so you'll have to do it through Humble Bundle.The devs said this to another guy when he asked about upgrading to the Bottomless Bag Teir:
http://secretsofgrindea.com/forum/index.php?threads/question-bottomless-bag-tier.4294/#post-11527

sorry for another question, but getting the bag tier while already having the slime tier, do I need to do anything fancy?

Humble Bundle has no built in support for "upgrading" so in the past we've just done it manually like this:

Buy another Slime Tier with the same e-mail as your first, and then tip* the amount needed to reach a total of $100. In your case, this would be $70!

$15 (Slime #1) + $15 (Slime #2) + $70 (Tip) = $100

Then just send us an e-mail and we'll gift you a Bottomless Bag!

* you add a tip by pressing the little plus-sign in the widget