Refund of excess excise credit

Dear All,

We have accumulated Cenvat Credit for the past 2 years.Our Unit basically does job work and very little of excisable sales.

As such the credit availed on machine purchases and other purchases lead to this accumuation of cenvat.A Small part of it is used to pay excise duty every month.

My Questions are,

1) Is it possible to Claim refund of Cenvat  in our case ? (We are not doing any export business)

2) Withing how many years the refund claim has to be made ? Is there a time-limit.

Please advice any possible way for the  recovery of  Cenvat credit in our account,

Regards

Lalitha