Cypress Hills Interprovincial Park straddles the Saskatchewan-Alberta boundary in the south.
A survey of the park by Great Western Forestry found more trees had been affected by the destructive bug than earlier believed.
The government has extended the company's contract so it can verify all infested trees and mark them for removal.
A similar survey in the boreal forest in northwestern Saskatchewan last fall did not find any pine beetles.
There are indications that the pest, which has destroyed large swaths of forest in British Columbia and areas of Alberta, is heading east.
The extra $100,000 to complete the Cypress Hills survey means the Saskatchewan government will have spent $300,000 this fiscal year to monitor the beetle.