https://www.slab.org.uk/guidance/the-importance-of-monitoring-your-case-costs-considering-sufficient-expenditure/
You should remain aware of all costs being incurred as a case progresses, including your own fees and any other outlays. You should have sufficient expenditure in place for all the work you need to undertake. If you are submitting an application for sanction, you should consider if you have enough funding available or if you need to seek an increase in the limit.
You may find it useful to obtain estimates of costs where the case requires:
This will allow you to keep a track of costs and to seek prospective increases where appropriate.
If you want to apply for exceptional case status, or an additional fee, this may have an impact on your case cost limit. If this is likely to take you over your case cost limit, then you must apply for an increase in the usual way.