Search limit and tips and tricks

So I have a lot of subscriptions that I use Zoho and Authorize.net to keep track of. This involves looking up a contact whenever Authorize.net charges them. Today, I found out the hard way that Zoho only allows me to lookup 250 records per day (even though I can update upwards of thousands?). So how do I go about being able to get full usage of my update limit, if I can't find out who needs to be updated using a lookup? Theoretically I can only update 250 unique contacts per day if I do happen to know their ID off the top of my head. Can I increase this limit? I only need to run a lot of searches on a single given day per month (ideally about 2000). Any tips or tricks would be appreciated.

Gabe