Hello. The database of DT Donate would not change in this migration, so you must not have migrated the old DT Donate database tables from your 1.0 database. Go to your 1.0 database, export all dtdonate tables, then import them into your 1.5 database.
Regarding your settings, prior to the recent 2.2.x releases, the DT Donate settings were stored in a FILE, not the database. This is described in your readme files. You need to grab your config.dtdonate.php file from the 1.0 site. Then you can take this and move it to your 1.5 site. As stated in the readme, you should backup that config file before uninstalling.
In the newer releases, settings are stored in the database so this is no longer a concern.