If you experience worsening it warrants addressing. At present there is no evidence that mood stabilizers such as lithium and divalproex are effective for PMS, so increasing the dose of one of these is not a first option.
Some women can get benefits with treatment limited to the two weeks before menses.
Since these medications can destabilize persons with bipolar disorder, either by causing manic states or increasing mood instability, the short, phasic use of one of these drugs may be a safer approach.