To avoid missing out on a lot that you're interested in, you can increase your maximum bid in one of two ways:
1. Go to My ELA and "My Current Bids"
2. Go directly to the lot page and edit
For Live Auctions:
You can increase, lower or remove your Autobid at any point up until the lot is offered for sale.
For Timed Auctions:
You can increase or lower your bid, however you cannot remove your bid.
For more advice on what to do if you have placed a timed bid in error, see this article (removing bids).