Sure, there are plenty of step-up chips available. Your case is easier than some because you don't need to worry about the input voltage exceeding the output voltage (3.2 is probably the highest voltage you can expect from two AA cells).
A reasonable minimum voltage is 1.6V for two cells. You could use the Skyworks chip as shown below- one of the cheapest and smallest solutions, but there are other modern chips that are similarly minimalist in their requirements and cost. Be sure to use the recommended layout, component types and one of the recommended inductor part numbers unless you really understand what is going on.
To prevent damage to the rechargable cells you may wish to have the circuit shut down at some minimum voltage. Many modern boost regulators will happily operate until they've completely flattened the cells (the above one will typically continue to operate to 250mV/cell).