Premier had suspended its shares on 13 January after agreeing to buy E.On's North Sea assets for a net $120m (Â£84m) plus working capital adjustments.
The deal was amended during the suspension so that it no longer constituted a reverse takeover.
By close of trading, Premier's share price was up by nearly 90% to 36p.
London-based Premier said the cost of the deal would now come to $135m, including completion adjustments.
Premier added that this was a result of an increase of the dividend paid to E.On before completion of the deal.
In a statement, it said: "On the basis of this lower aggregate consideration, the acquisition has been classified as a Class 1 transaction."
The proposed acquisition is still subject to approval by Premier's shareholders and lenders.
The assets Premier is buying are located in the Central North Sea, West of Shetlands and the Southern Gas Basin.
E.On's UK oil and gas upstream portfolio includes stakes in 40 licenses, including a 5.2% interest in the Elgin-Franklin field, a 47% interest in the Babbage field and a 50% stake in the Tolmount discovery.
The deal will add about 15,000 barrels of oil equivalent per day to Premier's production totals in 2016, according to the company.
Premier Oil's shares nearly doubled in value on Monday after trading was restarted following a suspension triggered by a major North Sea deal.