Once you have created a new Solicitation and you want to copy the schedule from a previous Solicitation, you can easily use templates.

Go to the original Solicitation that you want to copy the schedule from (you have to be a participant in the solicitation). Under the third tab 'Schedule' you'll find a 'Save as Template' link at the top right part of your screen.

Name and save the schedule template.

Now navigate to the solicitation, where you want to use the existing schedule. Go to the third tab again: 'Schedule' and now choose 'Import template' to load the existing schedule into your new solicitation.

Using this option, events are added to the schedule and all dates and times are re-used relative to the start date of this new solicitation.

I cannot select the template I've just created? 
If you are not able to re-use the schedule, most probably both solicitations have a different procedure with possible additional phase(s).
Look in the original solicitation and see what procedure was used under: Properties > Procedure, and make sure your new solicitation has the same procedure assigned to itThis is a prerequisite for importing a Schedule template.

Delete a Schedule template

Open a solicitation in preparation, go to Schedule. Click on Import template and select the template you want to delete. Click on the trash bin icon to delete the template.