Two Options: Any of these can work.
1. Have an Eloqua form instead of your existing form, Where once the Eloqua form is filled out, Eloqua can then repost data to your form, saving you the hastle of making significant changes to your website/page. Once the data is in Eloqua and user's are re-directed to another page, that's where you have can have another Eloqua hosted page.
2. Have your Form, also post the data (Repost) to Eloqua form, Once the data is in Eloqua and user's are re-directed to another page, that's where you have can have another Eloqua hosted page/form.
I recommend going with first option, since you do not have to do much coding. Deffinately perform a full production testing if you choose the first option.
Thanks
Amit