Welcome back Christiane,

This is currently supported on a per test case boundary while executing a test suite:

After each finished test case the test result is committed to the database for this test run.
You may abort the test run at any time by closing the execution window.
You may loose the current test case result this way when it not yet has been committed.

Under Execute / Continue Test Run you may continue that test run at any later date starting after the last committed test result.
The overall test execution time will correctly reflect the sum of the individual test execution times.

Does that satisfy your requirements?

Regards,

Torsten