Suppose you export your SSRS report to PDF extension format (or any other available formats) and your one page report gets broken down into two pages in PDF file, this can be taken care of by updating its 'Device Information Settings'.
The 'Device information settings' section also allows you to override the export extension names by overriding them.
There are other configurable settings as well which can be updated as needed.

Below is how you would do it:
Go to 'rsreportserver.config' at 'C:\Program Files\Microsoft SQL Server\MSSQL.2\Reporting Services\ReportServer' location and update the settings as follows:


<Extension Name="PDF" Type="Microsoft.ReportingServices.Rendering.ImageRenderer.PdfReport,Microsoft.ReportingServices.ImageRendering">
<Name Language="en-us">PDF (Updated)</Name>




The above updated settings increases the resolution and accommodates the report in one page in the exported PDF file.
Also, in the 'Export' drop down list, the overridden name "PDF (Updated)" would appear.

For more information on the available 'Device Information Settings' visit: