I would suggest that you run a full node (with pruning), and have your website send transactions to the network via your node.

In addition to your problem with blockr.io's API, with your current setup, you are risking that you will be unable to push any transactions when any part of the chain between you --> blockr.io --> blockr.io's node --> the rest of the network is broken.

You can setup your node so that it will delete the portion of the blockchain that goes back more than x MB (the default setting is 300 MB, but you can reduce this), and I believe you can change your node's settings so that it will only listen for new blocks (and not unconfirmed transactions), while still being able to relay new transactions that you wish to broadcast.