Eligibility service requirements cut off

Is there a way in the plan doc to cut off the need to look back to the beginning of the company to determine eligibility. For hours of service can we say you have to complete X hours of service within the last 5 years to be deemed eligible? I know there is the option for specified months - hours of service, but this still does not seem to take away from the fact that we would have to look back to the start of the company to determine if anyone ever met these requirements in case they are hired again.  We are trying to find a way to not have to look back to the beginning of the company in cases where people may be rehired to determine if they completed the eligibility requirements before. 

You'll want to read up on break in service rules, and rule of parity. Depending on the circumstance rehired employees can be made to resatisfy service for eligibility, and prior service disregarded. Your plan document (look at the basic plan document too if you have one) likely addresses that in detail.