I don't think there's something built in to InfoPath to achieve this, but one easy option is:
1. user clicks submit
2. Form submits
3. Switch views to a view that says: "Thank you. The form has been submitted. Click here for the next step"
4. Below this message, provide a clickable link that they can click on to open the next form.
The other option would be to write code and see if this can be accomplished via custom code, but I think the above should be an easy workaround.
Hope this helps!